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RD Sharma Class 12 Exercise 3.7 Inverse Trigonometric Function Solutions Maths - Download PDF Free Online

RD Sharma Class 12 Exercise 3.7 Inverse Trigonometric Function Solutions Maths - Download PDF Free Online

Updated on Jan 21, 2022 12:28 PM IST

The RD Sharma Solutions for Class 12 Mathematics have helped thousands of students score good marks in their public exams. It is the best guide for students to sharpen their mathematical skills whenever they find the time. Unfortunately, inverse Trsigonometry is not a concept that every student in a class would find accessible. But with the help of RD Sharma Class 12th exercie 3.7, they can perform well in their examinations.

Also Read - RD Sharma Solution for Class 9 to 12 Maths

RD Sharma Class 12 Solutions Chapter 3 Inverse Trigonometric Functions - Other Exercise

Inverse Trigonometric Functions Excercise: 3.7

Inverse Trignometric Functions exercise 3.7 question 1 (i)

Answer: π6
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1(sinπ6)
Explanation:
We know that the value of sinπ6 is 12
By substituting this value in sin1(sinπ6)
We get sin1(12)
Let,
y=sin1(12)siny=12siny=(12)sin(π6)=12
The range of principal value of sin1 is [π2,π2]
and sin(π6)=12
Therefore, sin1(sinπ6)=π6
Hence, sin1(sinθ)=θ with θ[π2,π2]sin1(sinπ6) is π6


Inverse Trignometric Functions exercise 3.7 question 1 (ii)

Answer: π6
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1(sin7π6)
Explanation:
First, we solve (sin7π6)
Sin7π6=sin(π+π6)
As we know sin(π6)=12
sin(π+π6)=sin(π6)sin[π+θ]=sin(θ)
sin1(sin7π6)=sin1(12)
Now,  let y=sin1(12)
siny=12sin(π6)=12sin(π6)=sin(π6)
The range of principal value of sin1(π2,π2) and sin(π6)=12
sin1(sinπ6)=π6{ As Sin7π6=sin(π+π6)}
As [sin1(sinx)]=x

Inverse Trignometric Functions exercise 3.7 question 1 (iii)

Answer: π6
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1(sin5π6)
Explanation:
First, we solve sin5π6
5π6=ππ6
Then,
sin(ππ6)=sin(π6)sin(πθ)=sin(θ)
We know that the value of sinπ6 is 12
sin5π6=12
By substituting this value in sin1(sin5π6)
we get sin1(12)
Let y=sin1(12)
siny=12sin(π6)=12
The range of principal value of sin1 is [π2,π2] and sin(π6)=12
sin1(sinπ6)=π6sin1(sin5π6)=π6[sin1(sinθ)=θ]

Inverse Trignometric Functions exercise 3.7 question 1 (iv)

Answer:

Answer: π7
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1(sin13π7)
Explanation:
First we solve (sin13π7)
13π7=2ππ7
sin(2ππ7)=sin(π7)[sin(2πθ)=sin(θ)]
By substituting these value in
sin1(sin13π7)=sin1(sinπ7)
As sin1(sinx)=x with x[π2,π2]
The range of principal value of sin1 is [π2,π2]
sin1(sin13π7)=π7

Inverse Trignometric Functions exercise 3.7 question 1 (v)

Answer: π8
Hint: The principal value branch of function sin1 is [π2,π2]
Given:
Explanation:
First we solve (sin17π8)
sin17π8=sin(2π+π8)sin(2π+π8)=sin(π8)[sin(2π+θ)=sin(θ)]
By substituting these values in sin1(sin17π8)
we get sin1(sinπ8)
 As sin1(sinx)=x with x[π2,π2]sin1(sin17π8)=π8


Inverse Trignometric Functions exercise 3.7 question 1 (vi)

Answer: π8
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1{(sin17π8)}
Explanation:
First we solve (sin17π8)
As we know, sinθ=sin(θ)
(sin17π8)=sin17π8sin17π8=sin(2π+π8)
sin(2π+π8)=sin(π8)[sin(2π+θ)=sin(θ)]
[sin(θ)=sin(θ)]sin(π8)=sin(π8)
By substituting these values in sin1{(sin17π8)} we get,
sin1(sinπ8)
 As sin1(sinx)=x with x[π2,π2]sin1(sinπ8)=π8

Inverse Trignometric Functions exercise 3.7 question 1 (vii)
Answer:

π3
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1(sin3)
Explanation:
We know that,sin1(sinx)=x with x[π2,π2] which is approximately equals to [1.57,1.57]
But here x=3 , which do not lie on the above range.
∴ We know that sin(πx)=sin(x)
sin(π3)=sin(3) also π3[π2,π2]sin1(sin3)=sin1(sinπ3) Then, sin1(sinπ3)=π3


Inverse Trignometric Functions exercise 3.7 question 1 (viii)

Answer:

π4
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1(sin4)
Explanation:
We know that sin1(sinx)=x with x[π2,π2] which is approximately equal to [1.57,1.57]
But x=4 , which do not lie on the above range
We know,
sin(πx)=sin(x)sin(π4)=sin(4) also π4[π2,π2]sin1(sin4)=sin1(sinπ4)
Then,
sin1(sinπ4)=π4

Inverse Trignometric Functions exercise 3.7 question 1 (ix)

Answer: 124π
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1(sin12)
Explanation:
We know that sin1(sinx)=x with x[π2,π2] which is approximately equal to [1.57,1.57]
But x=12, which do not lie on the above range
We know sin(2nπx)=sin(x)
Hence sin(2nπ12)=sin(12)
Here,
n=2 also 124π[π2,π2]sin1(sin12)=124π

Inverse Trignometric Functions exercise 3.7 question 1 (x)

Answer: π2
Hint: The principal value branch of function sin1 is [π2,π2]
Given: sin1(sin2)
Explanation:
We know that sin1(sinx)=x with x[π2,π2] which is approximately equal to[1.57,1.57]
But here x=2 , which do not lie on the above range,
we know that sin(πx)=sin(x)
sin(π2)=sin(2) also π2[π2,π2]sin1(sin2)=sin1(sinπ2)sin1(sinπ2)=π2

Inverse Trignometric Functions exercise 3.7 question 2 (i)

Answer: π4
Hint: The principal value branch of function cos1 is [0,π]
Given: cos1{cos(π4)}
Explanation:
We know that cos(π4)=cos(π4)[cos(θ)=cosθ]
Also know that, cos(π4)=12
By substituting these values in cos1{cos(π4)}
we get,
cos1(12)
Let y=cos1(12)
cosy=12
Hence, range of principal value of cos1 is [0,π] and cos(π4)=12
cos1{cos(π4)}=π4cos1(cosx)=x,x[0,π]

Inverse Trignometric Functions exercise 3.7 question 2 (ii)

Answer: 3π4
Hint: The principal value branch of function cos1 is [0,π]
Given: cos1(cos5π4)
Explanation:
First we solve cos5π4
cos5π4=cos(π+π4)cos(π+π4)=12[cos(θ)=cosθ]
As we know that cosπ4=12
cos(5π4)=12
By substituting these value in cos1{cos(5π4)}
we get,
cos1(12)
Since [cos(θ)=cosθ]
Let y=cos1(12)
cosy=12cos(π4)=12cos(ππ4)=12cos(3π4)=12
Hence, range of principal value of cos1 is [0,π] and cos(3π4)=12
cos1{cos(5π4)}=3π4cos1(cosx)=x,x[0,π]

Inverse Trignometric Functions exercise 3.7 question 2 (iii)

Answer: 2π3
Hint: The principal value branch of function cos1 is [0,π]
Given: cos1(cos4π3)
Explanation:
First we solve cos(4π3)
cos4π3=cos(π+π3)cos[π+θ]=cosθ
cos(π+π3)=12cos(4π3)=12
By substituting these value in cos1{cos(4π3)}
cos1(12)
Now,
Let y=cos1(12)
cosy=12cos(π3)=12cos(ππ3)=12cos(2π3)=12
Hence, range of principal value of cos1 is [0,π] and cos(2π3)=12
cos1(cos2π3)=2π3

Inverse Trignometric Functions exercise 3.7 question 2 (iv)

Answer: π6
Hint: The principal value branch of function cos1 is [0,π]
Given: cos1(cos13π6)
Explanation:
First we solve cos13π6
cos13π6=cos(2π+π6)[cos(2π+θ)]=cosθcos(2π+π6)=cos(π6)
=32cos(13π6)=32
By substituting these values in cos1(cos13π6)
we get,
cos1(32)
Now, lety=cos1(32)
cosy=32cos(π6)=32
Hence, range of principal value of cos1 is [0,π] and cosπ6=32
cos1(cosπ6)=π6cos1(cosx)=x,x[0,π]cos1{cos(13π6)}=π6

Inverse Trignometric Functions exercise 3.7 question 2 (v)

Answer: 3
Hint: The principal value branch of function cos1 is [0,π]
Given: cos1(cos3)
Explanation:
We know that
cos1(cos3)=3,3[0,π][cos1(cosθ)=θ if 0θπ]
Hence, the answer is cos1(cos3)=3

Inverse Trignometric Functions exercise 3.7 question 2 (vi)

Answer: 2π4
Hint: The principal value branch of function cos1 is [0,π]
Given: cos1(cos4)
Explanation:
We know that cos1(cosx)=x if x[0,π][0,3.14]

And herex=4 which do not lie in the above range

cos(2πx)=cos(x)cos(2π4)=cos(4)so2π4 belongs in [0,π]cos1(cos4)=2π4

Inverse Trignometric Functions exercise 3.7 question 2 (vii)

Answer: 2π5
Hint: The principal value branch of function cos1 is [0,π]
Given: cos1(cos5)
Explanation:
We know that cos1(cosx)=x if x[0,π][0,3.14]
And here x=5 which do not lie in the above range.
We know that cos(2πx)=cos(x)
cos(2π5)=cos(5)so2π5 belongs in [0,π]
Hence, cos1(cos5)=2π5

Inverse Trignometric Functions exercise 3.7 question 2 (viii)

Answer: 4π12
Hint: The principal value branch of function cos1 is [0,π]
Given: cos1(cos12)
Explanation:
We know that cos1(cosx)=x if x[0,π][0,3.14]
Herex=12 which do not lie in the above range.
We know that
cos(2nπx)=cos(x)cos(2nπ12)=cos12
Here, n=2
Also, 4π12 belongs in [0,π]
cos1(cos12)=4π12

Inverse Trignometric Functions exercise 3.7 question 3 (i)

Answer: π3
Hint: The principal value branch of function cos1 is [0,π]
Given: tan1(tanπ3)
Explanation:
As tan1(tanx)=x if x[π2,π2]
By applying this situation
we get
tan1(tanπ3)=π3
Hence, tan1(tanπ3) is π3

Inverse Trignometric Functions exercise 3.7 question 3 (ii)

Answer: π7
Hint: The range of principal value of tan1 is [π2,π2]
Given: tan1(tan6π7)
Explanation:

First we solve tan6π7

tan6π7=tan(ππ7)tan(ππ7)=tanπ7(tan(πθ)=tanθ)

We know

tan1(tanx)=x if x[π2,π2]

tan1(tan6π7)=π7

Inverse Trignometric Functions exercise 3.7 question 3 (iii)

Answer: π6
Hint: The range of principal value of tan1 is [π2,π2]
Given: tan1(tan7π6)
Explanation:
First we solve tan7π6
tan7π6=tan(π+π6)
As we know, tan(π+θ)=tanθ
tan(π+π6)=tanπ6tanπ6=13
By substituting this value in tan1(tan7π6) we get
tan1(13)
Now,  let tan1(13)=y
tany=13tan(π6)=13
The range of principal value of tan1 is [π2,π2] and tan(π6)=13
tan1(tan7π6)=π6 As tan1(tanx)=x,x[π2,π2]

Inverse Trignometric Functions exercise 3.7 question 3 (iv)

Answer: π4
Hint: The range of principal value of tan1 is [π2,π2]
Given: tan1(tan9π4)
Explanation:
First we solve tan9π4
tan9π4=tan(2π+π4)
tan(2π+θ)=tanθ
tan(2π+π4)=tanπ4tanπ4=1tan9π4=1
By substituting this value in tan1(tan9π4), we get
tan1(1)
let, tan1(1)=y
tany=1tan(π4)=1
The range of principal value of tan1 is [π2,π2] and tan(π4)=1
tan1(tan9π4)=π4tan1(tanx)=x,x[π2,π2]

Inverse Trignometric Functions exercise 3.7 question 3 (v)

Answer: 1
Hint: The range of principal value of tan1 is [π2,π2]
Given: tan1(tan1)
Explanation:
As we know tan1(tanx)=x if x[π2,π2]
By substituting this condition in given question
tan1(tan1)=1
Hence, tan1(tan1)=1

Inverse Trignometric Functions exercise 3.7 question 3 (vi)

Answer: 2π
Hint: The range of principal value of tan1 is [π2,π2]
Given: tan1(tan2)
Explanation:
As tan1(tanx)=x if x[π2,π2]
But here x=2 which does not belong to above range
tan(πθ)=tan(θ)tan(θπ)=tan(θ)tan(2π)=tan(2)
Now, 2πin the given range [π2,π2]
Hence, tan1(tan2)=2π

Inverse Trignometric Functions exercise 3.7 question 3 (vii)

Answer: 4π
Hint: The range of principal value of tan1 is [π2,π2]
Given: tan1(tan4)
Explanation:
As tan1(tanx)=x if x[π2,π2]
But here x=4 which does not belongs to above range
tan(πθ)=tan(θ)tan(θπ)=tanθtan(4π)=tan(4)
Now, 4π[π2,π2]
Hence, tan1(tan4)=4π

Inverse Trignometric Functions exercise 3.7 question 3 (viii)

Answer: 124π
Hint: The range of principal value of tan1 is [π2,π2]
Given: tan1(tan12)
Explanation:
As tan1(tanx)=x if x[π2,π2]
But here x=12 which does not belongs to above range
tan(2nπθ)=tan(θ)tan(θ2nπ)=tanθ
Here, n=2
tan(124π)=tan(12)
Now, 124π[π2,π2]
Hence,

Inverse Trignometric Functions exercise 3.7 question 4 (i)

Answer: π3
Hint: The range of principal value of sec1 is x[0,π],xπ2
Given: sec1(secπ3)
Explanation:
As sec1(secx)=x if x[0,π]{π2}
By applying this situation we get,
sec1(secπ3)=π3
Hence, sec1(secπ3)=π3

Inverse Trignometric Functions exercise 3.7 question 4 (ii)

Answer: 2π3
Hint: The range of principal value of sec1 is [0,π][π2]
Given: sec1(sec2π3)
Explanation:
As sec1(secx)=x if x[0,π]{π2}
By applying this situation we get,
sec1(sec2π3)=2π3
Hence, sec1(sec2π3)=2π3

Inverse Trignometric Functions exercise 3.7 question 4 (iii)

Answer: 3π4
Hint: The range of principal value of sec1 is [0,π][π2]
Given: sec1(sec5π4)
Explanation:
First we solve sec5π4
But (2π3π4) belongs to 3 quadrant
So, sec(2π3π4)=sec3π4
sec3π4=2sec3π4=2
By substituting these value in sec1(sec5π4) we get,
sec1(2)
Now,  let y=sec1(2)
secy=2
sec(π4)=2
sec(ππ4)sec(3π4)=2
The range of principal value of sec1 is [0,π]{π2}
sec1(sec3π4)=3π4sec1(secx)=x,x[0,π]{π2}

Inverse Trignometric Functions exercise 3.7 question 4 (iv)

Answer: π3
Hint: The range of principal value of sec1 is [0,π][π2]
Given: sec1(sec7π3)
Explanation:
First we solve sec7π3
sec(7π3)=sec(2π+π3)[sec(2π+θ)=secθ]
sec(2π+π3)=sec(π3)sec(π3)=2
By substituting these value in sec1(sec7π3) we get,
sec1(2)
Now,  let y=sec1(2)
secy=2sec(π3)=2
The range of principal value of sec1 is [0,π]{π2} and sec(π3)=2
sec1(secπ3)=π3sec1(secx)=x,x[0,π]{π2}

Inverse Trignometric Functions exercise 3.7 question 4 (v)

Answer: π5
Hint: The range of principal value of sec1 is [0,π][π2]
Given: sec1(sec9π5)
Explanation:
First we solve sec(9π5)
sec(9π5)=sec(2ππ5)[sec(2πθ)]=secθ
sec(2ππ5)=sec(π5)sec(9π5)=sec(π5)
By substituting these value in sec1(sec9π5) we get,
sec1(secπ5)sec1(secx)=x,x[0,π]{π2}sec1(secπ5)=π5
Hence, sec1(sec9π5)=π5

Inverse Trignometric Functions exercise 3.7 question 4 (vi)

Answer: π3
Hint: The range of principal value of sec1 is [0,π][π2]
Given: sec1{sec(7π3)}
Explanation:
First we solve sec(7π3)
As we know that sec(θ)=sec(θ)
sec(7θ3)=sec(7π3)sec(7π3)=sec(2π+π3)
sec(2π+π3)=sec(π3)[sec(2π+θ)=secθ]sec(π3)=2
By substituting these value in sec1{sec(7π3)} we get,
sec1(2)
Now,  let y=sec1(2)
 sec y=2sec(π3)=2
The range of principal value of sec1 is [0,π]{π2} and sec(π3)=2
sec1(secπ3)=π3sec1(secx)=x,x[0,π]{π2}
Hence, sec1(sec7π3)=π3

ma class 12 chapter Inverse Trignometric Functions exercise 3.7 question 4 (vi)

Answer:

Answer: π3
Hint: The range of principal value of sec1 is [0,π][π2]
Given: sec1{sec(7π3)}

Inverse Trignometric Functions exercise 3.7 question 4 (vii)

Answer: 3π4
Hint: The range of principal value of sec1 is [0,π][π2]
Given: sec1(sec13π4)
Explanation:
First we solve sec(13π4)
sec(13π4)=sec(4π3π4)
As we know [sec2πθ]=secθ
But here after subtract 3π4 it comes in III quadrant where sec is negative
sec(4π3π4)=sec(3π4)sec3π4=2sec(3π4)=2
By substituting these values in sec1(sec13π4) we get,
sec1(2)
Now,  let y=sec1(2)
secy=2secy=2sec(π4)=2sec(ππ4)=2sec(3π4)=2
The range of the principle value of sec1 is [0,π]{π2} and sec(3π4)=2
sec1(sec3π4)=3π4
sec1(secx)=x,x[0,π]{π2}

Inverse Trignometric Functions exercise 3.7 question 4 (viii)

Answer: π6
Hint: The range of principal value of sec1 is [0,π][π2]
Given: sec1(sec25π6)
Explanation:
First we solve sec25π6
sec(25π6)=sec(4π+π6)
As we know sec[2π+θ]=secθ
sec(4π+π6)=sec(π6)
As we know sec(π6)=233
By substituting these value in sec1(sec25π6) we get,
sec1(233)
Now,  let y=sec1(233)
secy=233sec(π6)=233
The range of principal value of sec1 is [0,π]{π2} and sec(π6)=233
sec1(sec25π6)=π6sec1(secx)=x,x[0,π]{π2}

Inverse Trignometric Functions exercise 3.7 question 5sub question (i)

Answer: π4
Hint: The range of principal value of cosec1 is [π2,π2]{0}
Given: cosec1(cosecπ4)
Explanation:
As we know,
cosec1(cosecx)=x when x[π2,π2]{0}
By applying this situation we get,
cosec1(cosecπ4)=π4

Inverse Trignometric Functions exercise 3.7 question 5 (ii)

Answer: π4
Hint: The range of principal value of cosec1 is [π2,π2]{0}
Given: cosec1(cosec3π4)
Explanation:
First we solve cosec(3π4)
cosec(3π4)=cosec(ππ4)
As we know, [cosec(πθ)=cosecθ]
cosec(ππ4)=cosec(π4)cosec(π4)=2
By substituting these values in cosec1(cosec3π4) we get,
cosec1(2)
Let, y=cosec1(2)
cosecy=2cosec(π4)=2
The range of the principal value of cosec1 is [π2,π2]{0} and cosec(π4)=2
cosec1(cosecπ4)=π4
Hence, cosec1(cosec3π4)=π4

Inverse Trignometric Functions exercise 3.7 question 5 (iii)

Answer: π5
Hint: The range of principal value of cosec1 is [π2,π2]{0}
Given: cosec1(cosec6π5)
Explanation:
First we solve cosec(6π5)
cosec(6π5)=cosec(π+π5)
As we know, cosec(π+θ)=cosecθ
Then, cosec(π+π5)=cosec(π5)
cosec(π5)=cosec(π5)
As cosec(x)=cosecx
By substituting this value in cosec1(cosec6π5) we get,
cosec1(cosec(π5))
As we know, cosec1(cosecx)=x when x[π2,π2]{0}
cosec1(cosec6π5)=π5

Inverse Trignometric Functions exercise 3.7 question 5 (iv)

Answer: π6
Hint: The range of principal value of cosec1 is [π2,π2]{0}
Given: cosec1(cosec11π6)
Explanation:
First we solve cosec(11π6)
cosec(11π6)=cosec(2ππ6)
As we know, cosec(2πθ)=cosec(θ)
cosec(2ππ6)=cosec(π6)
As we know, cosec(π6)=2
cosec(π6)=2
By substituting these values in cosec1(cosec11π6) we get,
cosec1(2)
Let, y=cosec1(2)
cosecy=2cosecy=2cosec(π6)=2
As we know cosec(θ)=cosecθ
cosecπ6=cosec(π6)
The range of principal value of cosec1 is [π2,π2]{0} and cosec(π6)=2
cosec1(cosec(11π6))isπ6

Inverse Trignometric Functions exercise 3.7 question 5 (v)

Answer:

Answer: π6
Hint: The range of principal value of cosec1 is [π2,π2]{0}
Given: cosec1(cosec13π6)
Explanation:
First we solve
cosec(13π6)=cosec(2π+π6)
As we know cosec(2π+θ)=cosecθ
csc(2π+π6)=csc(π6)=2
By substituting these value in cosec1(cosec13π6) we get,
cosec1(2)
Now,  let y=cosec1(2)
cosecy=2cosec(π6)=2
The range of the principal value in cosec1 is [π2,π2]{0} and cosec(π6)=2
cosec1(cosec13π6) is π6cosec1(cosecx)=x,x[π2,π2]{0}

Question:5.6

Inverse Trignometric Functions exercise 3.7 question 5 (vi)

Answer: π4
Hint: The range of principal value of cosec1 is [π2,π2]{0}
Given: cosec1{cosec(9π4)}
Explanation:
First we solve cosec(9π4)
As we know cosec(θ)=cosecθ
cosec(9π4)=cosec(9π4)cosec(9π4)=cosec(2π+π4)cosec(2π+π4)=cosec(π4)
As we know
cosec(θ)=cosec(θ)cosec(π4)=cosec(π4)
Now it becomes cosec1(cosecπ4)
cosec1(cosecx)=x provide dx[π2,π2]{0}cosec1(cosec(π4))=π4

Inverse Trignometric Functions exercise 3.7 question 6 (i)

Answer: π3
Hint: The range of principal value of cot1 is [0,π]
Given: cot1(cotπ3)
Explanation:
As we know
cot1(cotx)=x provided x[0,π]
By apply this situation we get,
cot1(cotπ3)=π3

Inverse Trignometric Functions exercise 3.7 question 6 (ii)

Answer: π3
Hint: The range of principal value of cot1x is [0,π]
Given: cot1(cot4π3)
Explanation:
First we solve cot4π3
cot(4π3)=cot(π+π3)
As we know cot(π+θ)=cotθ
cot(π+π3)=cotπ3cotπ3=33
By substituting these value cot1(cot4π3) we get,
cot1(33)
Now,  let y=cot1(33)
coty=33cot(π3)=33
The range of the principal value of cot1 is [0,π]
cot1(cot4π3)=π3cot1(cotx)=x,x[0,π]

Inverse Trignometric Functions exercise 3.7 question 6 (iii)

Answer: π4
Hint: The range of principal value of cot1 is [0,π]
Given: cot1(cot9π4)
Explanation:
First we solve cot9π4
cot9π4=cot(2π+π4)cot(2π+θ)=cotθcot(2π+π4)=cotπ4cotπ4=1
By substituting these value in cot1(cot9π4) we get,
cot1(1)
Now,  let y=cot1(1)
coty=1cot(π4)=1
The range of principal value of cot1 is [0,π] and cot(π4)=1
cot1(cotπ4)=π4cot1(cotx)=x,x[0,π]

Inverse Trignometric Functions exercise 3.7 question 6 (iv)

Answer: π6
Hint: The range of principal value of cot1 is [0,π]
Given: cot1(cot19π6)
Explanation:
First we solve cot(19π6)
cot(19π6)=cot(3π+π6)
As we know, cot(nπ+θ)=cotθ
cot(3π+π6)=cotπ6cotπ6=3 [cot30=3]
By substituting these value in cot1(cot19π6) we get,
cot1(3)
Now,  let y=cot1(3)
coty=3cot(π6)=3
The range of the principal value of cot1 is [0,π] and cot(π6)=3
cot1(cotπ6)=π6
As we know, cot1(cotx)=x,x[0,π]

Inverse Trignometric Functions exercise 3.7 question 6 (v)

Answer: π3
Hint: The range of principal value of cot1 is [0,π]
Given: cot1{cot(8π3)}
Explanation:
First we solve cot(8π3)
As we know cot(θ)=cotθ
cot(8π3)=cot(8π3)cot(8π3)=cot(3ππ3)
As we know, cot(2πθ)=cotθ
cot(3ππ3)=cot(π3)=cot(π3)cot(π3)=13
By substituting these values in cot1(cot(8π3)) we get,
cot1(13)
Now,
Let y=cot1(13)
coty=13cot(π3)=13
The range of the principal value of cot1 is [0,π]
cot1(cotπ3)=π3cot1(cotx)=x, where x[0,π]

Inverse Trignometric Functions exercise 3.7 question 6 (vi)

Answer: π4
Hint: The range of principal value of cot1 is [0,π]
Given: cot1{cot(21π4)}
Explanation:
First we solve cot(21π4)
cot(21π4)=cot(5π+π4)
As we know cot(nπ+θ)=cotθ where n is (1,2,3,)
cot(5π+π4)=cot(π4)[cotπ4=1]
cot(π4)=1
By substituting these values in cot1{cot(21π4)} we get,
cot1(1)
Now ,  let y=cot1(1)
coty=1cot(π4)=1
The range of principal value of cot1 is [0,π] and cot(π4)=1
cot1(cotπ4)=π4cot1(cotx)=x,x[0,π]

Inverse Trignometric Functions exercise 3.7 question 7 (i)

Answer: sec1xa
Hint: The range of principal value of cot1 is [0,π]
Given: cot1{ax2a2},|x|>a
Explanation:
Let x=asecθ
Now, we put value of x in given question.
cot1{a(asecθ)2a2}cot1{aa2sec2θa2}cot1{aa2(sec2θ1)}
As we know 1+tan2θ=sec2θ
sec2θ1=tan2θcot1{aa2tan2θ}
Now we remove square root
cot1{aatanθ}cot1{1tanθ}
As we know, cotθ=1tanθ
cot1(cotθ)=θ
As we know, cot1(cotθ),θ[0,π]
x=asecθθ=sec1xa
Hence, cot1{ax2a2},|x|>a is sec1xa

Inverse Trignometric Functions exercise 3.7 question 7 (ii)

Answer: π212cot1x
Hint: The range of principal value of tan1 is [π2,π2]

Given: tan1{x+1+x2},xR
Explanation:
Let x=cotθ;θ=cot1x
Now ,
tan1{x+1+x2}=tan1{cotθ+1+cot2θ}
As we know, 1+cot2θ=cosec2θ
tan1{cotθ+cosec2θ}tan1{cotθ+cosecθ}
As we know, cotθ=cosθsinθsinθ=1cosecθ
tan1{cosθsinθ+1sinθ}tan1{cosθ+1sinθ}
As we know, sin2θ=2sinθcosθ
1+cosx=2cos2(x2)tan1{2cos2θ22sinθ2cosθ2}
tan1{cosθ2sinθ2}tan1{cotθ2}
As we know tanθ=cot(π2θ)
tan1{tan(π2θ2)}
As we know tan1(tanx)=x where x[π2,π2]
(π2θ2)
Now put value of θ
π2cot1x2

Inverse Trignometric Functions exercise 3.7 question 7 (iii)

Answer: 12cot1x
Hint: The range of principal value of tan1 is [π2,π2]

Given: tan1{1+x2x},xR

Explanation:
Let x=cotθ;θ=cot1x
Now,
tan1{1+x2x}=tan1{1+cot2θcotθ}
As we know, 1+cot2θ=cosec2θ
tan1{cosec2θcotθ}tan1{cosecθcotθ}
As we know, cotθ=cosθsinθ,cosecθ=1sinθ
tan1{1sinθcosθsinθ}tan1{1cosθsinθ}
1cosx=2sin2x2sinx=2sinx2cosx2
tan1{2sin2θ22sinθ2cosθ2}tan1[sinθ2cosθ2]tan1(tanθ2)
As we know, the principal range of tan1 is [π2,π2]
tan1(tanx)=x,x[π2,π2]
θ2
12cot1x

Inverse Trignometric Functions exercise 3.7 question 7 (iv)

Answer: 12tan1x
Hint: The range of principal value of tan1 is [π2,π2]

Given: tan1{1+x21x},x0
Explanation:
Let x=tanθ, then θ=tan1x
tan1(1+x21x)=tan1(1+tan2θ1tanθ)
As we know, 1+tan2θ=sec2θ
tan1(sec2θ1tanθ)tan1(secθ1tanθ)
tan1(1cosθ1sinθcosθ)[secθ=1cosθ,tanθ=sinθcosθ]
tan1(1cosθcosθsinθcosθ)
tan1(1cosθcosθ×cosθsinθ)
tan1(1cosθsinθ)
tan1[2sin2θ22sinθ2cosθ2][sin2θ=2sinθcosθ1cosθ=2sin2θ2]
tan1[sinθ2cosθ2]tan1[tanθ2]
As we know tan1(tanx)=x,x[π2,π2]
tan1[tanθ2]=θ2
Now putting the value of θ
12tan1x

Inverse Trignometric Functions exercise 3.7 question 7 (v)

Answer: π212tan1x
Hint: The range of principal value of tan1 is [π2,π2]

Given: tan1{1+x2+1x},x0
Explanation:
Put x=tanθ, then θ=tan1x
tan1(1+x2+1x)=tan1(1+tan2θ+1tanθ)
As we know, 1+tan2θ=sec2θ
tan1(sec2θ+1tanθ)tan1(secθ+1tanθ)
tan1(1cosθ+1sinθcosθ)[secθ=1cosθ,tanθ=sinθcosθ]
tan1(1+cosθcosθsinθcosθ)tan1(1+cosθcosθ×cosθsinθ)tan1(1+cosθsinθ)
tan1[2cos2θ22sinθ2cosθ2][sin2θ=2sinθcosθ1+cosθ=2cos2θ2]
tan1[cotθ2]
tanθ=cot(π2θ)tan1(tan(π2θ2))
As we know the range of principal value of tan1 is [π2,π2]
tan1(tanx)=x,x{π2,π2}π2θ2π212tan1x

Inverse Trignometric Functions exercise 3.7 question 7 (vi)

Answer: 12cos1xa
Hint: The range of principal value of tan1 is [π2,π2]

Given: tan1axa+x,a<x<a
Explanation:
Let x=acosθ
then θ=cos1xa
Now,
tan1axa+x=tan1aacosθa+acosθ
tan1a(1cosθ)a(1+cosθ)tan11cosθ1+cosθ
tan12sin222cos2θ2[1+cosx=2cos2(x2)1cosx=2sin2(x2)]
tan1tan2θ2sinθcosθ=tanθ
tan1(tanθ2)
As we know, tan1(tanx)=x,x[π2,π2]
θ212cos1xa

Inverse Trignometric Functions exercise 3.7 question 7 (vii)

Answer: 12sin1xa
Hint: The range of principal value of tan1 is [π2,π2]

Given: tan1[xa+a2x2],a<x<a
Explanation:
Put x=asinθ, then θ=sin1xa
tan1[asinθa+a2a2sin2θ]
tan1[asinθa+a2(1sin2θ)][sin2θ+cos2θ=1]
tan1[asinθa+a2cos2θ]tan1[asinθa+acosθ]
tan1[asinθa(1+cosθ)]tan1[sinθ1+cosθ]
[sin2θ=2sinθcosθcos2x=2cos2x1]
tan1{2sinθ2cosθ21+2cos2θ21}
tan1[sinθ2cosθ2]tan1[tanθ2]
As we know, tan1(tanx)=x,x[π2,π2]
θ212sin1xa

Inverse Trignometric Functions exercise 3.7 question 7 (viii)

Answer: π4+sin1x
Hint: The range of principal value of sin1 is [π2,π2]

Given: sin1[x+1+x22],12<x<12
Explanation:
Let x=sinα
Then α=sin1x
x+1x22=sinα+1sin2α2sin2α+cos2α=1
Then, 1sin2α=cos2α
=sinα+cos2α2=sinα+cos2α2
=(sinα12+cosα12)cos(π4)=12,sin(π4)=12
=sinαcos(π4)+cosαsin(π4)sinAcosB+cosAsinB=sin(A+B)
sinαcos(π4)+cosαsin(π4)=sin(α+π4)
Then put value of x+1x22=sin(α+π4)
sin1(sin(α+π4))
As we know, sin1(sinx)=x,x[π2,π2]
=α+π4=sin1x+π4

Inverse Trignometric Functions exercise 3.7 question 7 (ix)

Answer: π4+12cos1x
Hint: The range of principal value of sin1 is [π2,π2]

Given: sin1[1+x+1x2],0<x<1
Explanation:
Let x=cosθ
Then
θ=cos1x
Now,
sin1[1+x+1x2]=sin1[1+cosθ+1cosθ2]
1+cosx=2cos2(x2)&1cosx=2sin2(x2)
sin1{2cos2θ2+2sin2θ22}sin1{2cosθ2+2sinθ22}
sin1{2(cosθ2+sinθ2)2}{2×2=2}
sin1{2(cosθ2+sinθ2)2×2}sin1{cosθ2+sinθ22}sin1{12sinθ2+12cosθ2}
sin1{sin(θ2+π4)}sin1(sinθ)=θ,θ[π2,π2]
=θ2+π2=cos1x2+π4sin1{1+x+1x2}=cos1x2+π4

Inverse Trignometric Functions exercise 3.7 question 7 (x

Answer: 1x2
Hint: The range of principal value of sin1 is [π2,π2]

Given: sin[2tan11x1+x]
Explanation:
First we solve 2tan1x1+x
Let x=cos2A
Therefore,
2tan11x1+x=2tan11cos2A1+cos2A
[1cos2x=2sin2x&1+cos2A=2cos2A]
=2tan12sin2A2cos2A
=2tan1tan2A=2tan1(tanA)
As we know, tan1(tanx)=x,x[π2,π2]
=2tan1(tanA)=2A
Therefore,
sin[2tan11x1+x]
=sin2A(1sin2θ=cos2θ)
=1cos22A
Now put value of cos2A=x
1cos22A=1x2

In Chapter 3, Inverse Trigonometry for Class 12 Mathematics, about 14 exercises in total. In Exercise 3.7, there are many different functions that the students are asked to work out. The concepts include solving sine, cosine, tangent, cotangent, secant, and cosecant functions. There are fifty-six questions, including the subparts in exercise 3.7. And the RD Sharma Class 12 Solution Chapter 3 Exercise 3.7 book will make your work effortless.

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