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RD Sharma Class 12 Exercise 27.5 Straight line in space Solutions Maths - Download PDF Free Online

RD Sharma Class 12 Exercise 27.5 Straight line in space Solutions Maths - Download PDF Free Online

Edited By Lovekush kumar saini | Updated on Jan 25, 2022 09:48 AM IST

RD Sharma books think of another form sporadically, and it gets hard for students to monitor the most recent rendition materials. This implies that when the new record is delivered, the more conventional materials become less accommodating. RD Sharma solutions For example, class 12 RD Sharma chapter 27 exercise 27.5 arrangement via Career360 is refreshed to the most recent rendition, which implies that students will not need to stress over absence or various inquiries.

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RD Sharma Class 12 Solutions Chapter27 Straight line in space - Other Exercise

Straight Line in Space Excercise: 27.5

Straight Line in Space exercise 27.5 question 1(i)

Answer:d=3302
Hint: Using formula $a \frac{\left|x2x1y2y1z2z1a1b1c1a2b2c2\right|}{\sqrt{\left(a_{1} b-a_{2} b_{1}\right)^{2}+\left(b_{1} c_{2}-b_{2} c_{1}\right)^{2}+\left(a_{1} c_{2}-a_{2} c_{1}\right)^{2}}}$

Given: γ=(3ı^+8ȷ^+3k^)+λ(3ı^ȷ^+k^) and (3ı^ȷ^+k^)+μ(7ı^6ȷ^+k^)

Solution: From the given pair of equation
$x33=y81=z311x+33=y+72=z642$
$d=\frac{\left|6153311324\right|}{\sqrt{(6-3)^{2}+(-4-2)^{2}+(12+3)^{2}}}$
$=|6(42)15(12+3)3(63)9+36+225|=362259270$
$=270270=270=330ANS$

Straight Line in Space exercise 27.5 question 1(ii)

Answer:D=6462 units 
Hint: Using formula d=|(a2a1)(b1×b2)||(b1×b2)|

Given:γ=(3ı^+5ȷ^+7k^)+λ(ı^2ȷ^+7k^) and γ=(ı^ȷ^k^)+μ(7ı^6ȷ^+k^)

Solution:
$a1=3ı^+5ȷ^+7k^a2=ı^ȷ^k^b1=ı^2ȷ^+7k^b2=7ı^6ȷ^+k^$
The shortest distance between the lines is
$d=|(a2a1)(b1×b2)||(b1×b2)|(a2a1)=(ı^ȷ^k^)(3ı^+5ȷ^+7k^)=4ı^6ȷ^8k^$
$(b1×b2)=|ı^ȷ^k^127761|(b1×b2)=(2+42)+[(149)j^]+(6+14k^)=40ı^+48ȷ^+8k^$
$|b1×b2|=(40)2+(48)2+(8)2=862$
$|(a2a1)(b1×b2)|=|(4ı^6ȷ^8k^)(40ı^+48ȷ^+8k^)||(a2a1)(b1×b2)|=|512|=512$
Putting the values in the above mentioned formula,
$d=512862=6462=6462 units $

Straight Line in Space exercise 27.5 question 1(iii)

Answer: d=16 units 
Hint: Using formula d=|(a2a1)(b1×b2)||(b1×b2)|

Given: γ=(ı^+2ȷ^+3k^)+λ(2ı^+3ȷ^+4k^) and γ=(2ı^+4ȷ^+5k^)+μ(3ı^+4ȷ^+5k^)
Solution:
By the given pairs of equation,
$a1=ı^+2ȷ^+3k^a2=2ı^+4j^+5k^b1=2ı^+3ȷ^+5k^b2=3ı^+4ȷ^+5k^$
The shortest distance between the lines is,
$(a2a1)=(2ı^+4ȷ^+5k^)(ı^+2ȷ^+3k^)(a2a1)=ı^+2ȷ^+2k^$
$(b1×b2)=|ı^ȷ^k^234345|(b1×b2)=ı^+2ȷ^k^$
$|b1×b2|=(1)2+(2)2+(1)2|b1×b2|=6|(a2a1)(b1×b2)|=|(ı^+2ȷ^+2k^)(ı^+22ȷ^k^)|1$
Putting three values in the expression,
$d=|(a2a1)(b1×b2)||(b1×b2)|d=16 units $

Straight Line in Space exercise 27.5 question 1(iv)

Answer: d=829 units 
Hint: Using formula =|(ca)(b×d)||(b×d)| and convert the given equation in normal forms.

Given: γ=(1t)ı^+(t2)ȷ^+(3t)k^ and γ=(s+)ı^+(2s1)ȷ^(2s+1)k^
Solution:
$γ=(ı^+2ȷ^+3k^)+t(ı^+ȷ^2k^)[γ=a+λb]γ=(ı^ȷ^k^)+s(ı^+2ȷ^2k^)[γ=c+λd]$
$\vec{b} \times \vec{d}=\left|ı^ȷ^k^112122\right|$
=ı^[1(2)(2)(2)]ȷ^[(1)(2)(1)(2)]+k^[(1)(2)(1)(1)]
$b×d=2ı^4ȷ^3k^|b×d|=(2)2+(4)2+(3)29+16+429$
$(ca)=(ȷ^4k^)d=|(ȷ^4k^)(2ı^4ȷ^3k^)||29||04+12||29|829$

Straight Line in Space exercise 27.5 question 1(v)

Answer: d=522 units 
Hint: Convert the given equation in the normal form γ=a+λb
$ Let γ=a1+λb1γ=a2+μb2$
Given: γ=(λ1)ı^+(λ+1)ȷ^(1+λ)k^ and γ=(1μ)ı^+(2μ1)ȷ^+(μ+2)k^
Solution:
$γ=(ı^+ȷ^k^)+λ(ı^+ȷ^k^) and γ=(ı^ȷ^+2k^)+μ(ı^+2ȷ^+k^)D=|(a2a1)(b1×b2)||(b1×b2)|$
Here
$a1=ı^+ȷ^k^b1=ı^+ȷ^k^a2=ı^ȷ^+2k^b2=ı^(a2a1)=2i^2ȷ^+3k^$
$\left(\overrightarrow{b_{1}} \times \overrightarrow{b_{2}}\right)=\left|ı^ȷ^k^111121\right|$
$b1×b2=ı^(1+2)ȷ^(11)+k^(2+1)=3ı^+3k^$
$|b1×b2|=(3)2+(3)232(a2a1)(b1×b2)=(2ı^2ȷ^+3k^)(3ı^+3k^)6+915D=1532152522$

Straight Line in Space exercise 27.5 question 1(vi)

Answer: d=32 units 
Hint: Using the expression d=|(a2a1)(b1×b2)||(b1×b2)|

Given: γ=(2ı^ȷ^k^)+λ(2ı^5ȷ^+2k^) and γ=(ı^+2j^+k^)+μ(ı^ȷ^+k^)
Solution:
$a1=2ı^ȷ^k^b1=2ı^5ȷ^+2k^a2=ı^+2ȷ^+k^b2=ı^ȷ^+k^$
The shortest distance between the lines is,
$(a2a1)=(ı^+2ȷ^+k^)(2ı^ȷ^k^)(a2a1)=ı^+3ȷ^+2k^$
$\left(\overrightarrow{b_{1}} \times \overrightarrow{b_{2}}\right)=\left|ı^ȷ^k^252111\right|$
$(b1×b2)=(5+2)ı^(22)ȷ^+(2+5)k^|b1×b2|=(3)2+(0)2+(3)2|b1×b2|=32$
|(a2a1)(b1×b2)|=|(ı^+3ȷ^+2k^)(3ı^+0ȷ^+3k^)|9
Putting three values in the above mentioned equation,
$d=932d=32 units $

Straight Line in Space exercise 27.5 question 1(vii)

Answer: d=1059 units 
Hint: Using the expression d=|(a2a1)(b1×b2)||(b1×b2)|
Given: γ=(ı^+ȷ^)+λ(2ı^ȷ^+k^) and γ=(2ı^+ȷ^k^)+μ(3ı^5ȷ^+2k^)
Solution: We know that,
$a1=ı^+ȷ^b1=2ı^ȷ^+k^a2=2ı^+ȷ^k^b2=3ı^5ȷ^+2k^$
It can be written as,
$(b1×b2)=|ı^ȷ^k^211352|(b1×b2)=(2+5)ı^(43)ȷ^+(10+3)k^(b1×b2)=3ı^ȷ^7k^$
$|b1×b2|=(3)2+(1)2+(7)29+1+4959(a2a1)=(21)ı^(11)ȷ^+(10)k^=ı^+0ȷ^k^$
We can write as,
$(b1×b2)(a2a1)=(3ı^ȷ^7k^)(ı^+0ȷ^k^)=(3×1)+[(1)×0]+([(7)×(1)=3+0+710$
The shortest distance between the given lines is,
d=|(a2a1)(b1×b2)||(b1×b2)|1059 units 

Straight Line in Space exercise 27.5 question 1(viii)

Answer: d=14 units 
Hint: Using the expression to find d=|(a2a1)(b1×b2)||(b1×b2)|

Given: γ=(8+3λ)ı^(9+16λ)ȷ^+(10+7λ)k^ and γ=(15ı^+29ȷ^+5k^)+μ(3ı^+8ȷ^2k^)

Solution: We know that,
$a1=8ı^9ȷ^+10k^b1=3ı^16ȷ^+7k^a2=15ı^+29ȷ^+5k^b2=3ı^+8ȷ^5k^$
The shortest distance between the given lines is,
$(a2a1)=(15ı^+29ȷ^+5k^)(8ı^9ȷ^10k^)(a2a1)=7ı^+38ȷ^5k^(b1×b2)=|ı^ȷ^k^3167385|$
$(b1×b2)=(8056)ı^(1521)ȷ^+(24+48)k^(b1×b2)=24ı^+36ȷ^+72k^4(6ı^+8ȷ^+18k^)$
$|b1×b2|=4(6)2+(9)2+(18)244414×2184|(a2a1)(b1×b2)|=|4(7ı^+38ȷ^5k^)(6ı^+9ȷ^+18k^)|4(42+34290)1176$
Putting three values in the above mentioned equation,
$d=117684d=14 units $

Straight Line in Space exercise 27.5 question 2(ii)

Answer: d=16 units 
Hint: Using the expression to find d=|(a2a1)(b1×b2)||(b1×b2)|
Given: :x12=y23=z34(1) and x23=y34=z54(2)
Solution: Since the given line (1) passes through the point (1,2,3) and has direction ratios proportional to (2,3,4) its vector equation is γ=a1+λb1
Here,
$a1=ı^+2ȷ^+3k^b1=2ı^+3ȷ^+4k^$
Also line (2) passes through the point (2,3,5) and has direction ratios proportional to (3,4,5) its vector equation is γ=a2+μb2
Here,
$a2=2ı^+3ȷ^+5k^b2=3ı^+4ȷ^+5k^$
Now,
$(a2a1)=ı^+j^+2k^(b1×b2)=|ı^ȷ^k^234345|=ı^+2ȷ^k^$
$|b1×b2|=(1)2+(2)2+(1)26 and (a2a1)(b1×b2)=(ı^+ȷ^+2k^)(ı^+2ȷ^k^)1+221$
The shortest distance between the given lines is,
d=|16|16 units 

Straight Line in Space exercise 27.5 question 2(ii)

Answer: d=359 units 
Hint: Consider the given equation as (1) and (2) and using the expression d=|(a2a1)(b1×b2)||(b1×b2)|
Given: :x12=y+13=z(1) and x+13=y21;z=2(2)
Solution:
Since line (1) passes through the point (1,1,0) and has direction ratios proportional to (2,3,1) its vector equation is γ=a1+λb1
Here,
$a1=ı^ȷ^+0k^b1=2ı^+3ȷ^+k^$
Also line (2) passes through the point (1,2,2) and has direction ratios proportional to (3,1,0) its vector equation is γ=a2+μb2
Here,
$a2=ı^+2ȷ^+2k^b2=3ı^+ȷ^+0k^$
Now,
$(a2a1)=2ı^+2ȷ^+2k^(b1×b2)=|ı^ȷ^k^231310|=ı^+3ȷ^7k^$
$|b1×b2|=(1)2+(3)2+(7)21+9+4959 and (a2a1)(b1×b2)=(2ı^+3ȷ^+2k^)(ı^+3ȷ^7k^)2+9143$
The shortest distance between the lines γ=a1+λb1 and V=a2+μb2 is given by
d=|359|359 units 

Straight Line in Space exercise 27.5 question 2(iii)

Answer:d=829 units 
Hint: Consider the given equation as (1) and (2)
Given:x11=y+21=z32(1) and x11=y+12=z+12(2)
Solution: Since line (1) passes through the point (1,2,3) and has direction ratios proportional to (1,1,2) its vector equation is γ=a1+λb1
Here,
$a1=ı^2ȷ^+3k^b1=ı^+ȷ^2k^$
Also line (2) passes through the point (1,1,1) and has direction ratios proportional to (1,2,2) its vector equation is γ=a2+μb2
Here,
$a2=ı^ȷ^k^b2=ı^+2ȷ^2k^$
Now,
$(a2a1)=ȷ^2k^(b1×b2)=|ı^ȷ^k^112122|=2ı^uȷ^3k^$
|b1×b2|=(2)2+(4)2+(3)24+16+929 and 
The shortest distance between the lines
$d=|(a2a1)(b1×b2)||(b1×b2)|d=|829|829 units $

Straight Line in Space exercise 27.5 question 2(iv)

Answer: d=229 units 
Hint:  Put λ=0 and k=0
Given: :x31=y52=z71(1) and x+17=y+16=z+11(2)
Solution:

Now, let’s take a point on first line as A(λ+3,2λ+5,λ+7) and let B(7k1,6k1,k1) be point on the second line.
The direction ratio of the line;
(7kλ4)×1+(6k+2λ6)×(2)+(kλ8)×1=0 Line (1) and 
(7kλ4)×7+(6k+2λ6)×(6)+(kλ8)×1=0 Line(2) 
Solving equation (1) and (2) we get
$λ=0 and k=0A=(3,5,7) and B=(1,1,1)AB=(3+1)2+(5+1)2+(7+1)216+32+64116229 units $

Straight Line in Space exercise 27.5 question 3(i)

Answer: Given Lines are not interesting
Hint: Using the equation d=|(a2a1)(b1×b2)||(b1×b2)|
Given: γ=(ı^ȷ^)+λ(2ı^+k^) and γ=(2ı^ȷ^)+μ(ı^+ȷ^+k^)
Solution:
We know that,
$a1=ı^ȷ^+0k^b1=2ı^+0ȷ^+k^a2=2ı^ȷ^b2=ı^+ȷ^k^$
The shortest distance between the lines is,
$(a2a1)=(2ı^ȷ^)(ı^ȷ^+0k^)(a2a1)=ı^+0ȷ^+0k^(b1×b2)=|ı^ȷ^k^201111|$
$(b1×b2)=(01)ı^(21)ȷ^+(20)k^(b1×b2)=ı^+3ȷ^+2k^|b1×b2|=(1)2+(3)2+(2)214|(a2a1)(b1×b2)|=|(ı^+0ȷ^+0k^)(ı^+3ȷ^+2k^)|1$
Putting three values in the above mentioned equation,
$d=114d=114 units $
∴ Shortest distance d between the lines is not 0, so lines are not intersecting.

Straight Line in Space exercise 27.5 question 3(ii)

Answer: Given Lines are not interesting
Hint: Using the equation d=|(a2a1)(b1×b2)||(b1×b2)|
Given: γ=(ı^+ȷ^k^)+λ(3ı^ȷ^) and γ=(4ı^k^)+μ(2ı^+3k^)
Solution:
We know that,
$a1=ı^+ȷ^k^b1=3ı^1ȷ^+0k^a2=4ı^+0ȷ^k^b2=2ı^+0ȷ^+3k^$
The shortest distance between the lines is,
$(a2a1)=(4ı^+0ȷ^k^)(ı^+ȷ^k^)(a2a1)=3ı^ȷ^+0k^(b1×b2)=|ı^ȷ^k^310203|$
$(b1×b2)=(30)ı^(90)ȷ^+(0+2)k^(b1×b2)=3ı^9j^+2k^|b1×b2|=(3)2+(9)2+(2)294|(a2a1)(b1×b2)|=|(3ı^1ȷ^+0k^)(3ı^9ȷ^+2k^)|0$
Putting three values in the above mentioned equation,
$d=094d=0$
∴ Shortest distance d between the lines is 0, so lines are intersecting.

Straight Line in Space exercise 27.5 question 3(iii)

Answer: Given Lines are not interesting
Hint: Consider the given equation as (1) and (2)
Given: :x12=y+13=z(1) and x+15=y21;z=2(2)
Solution: Since line (1) passes through the point (1,1,0) and has direction ratios proportional to (2,3,1) its vector equation is γ=a1+λb1
Here
$a1=ı^1ȷ^+0k^b1=2i^+3j^+k^$
Also line (2) passes through the point (1,2,2) and has direction ratios proportional to(5,1,0) its vector equation isγ=a2+μb2
Here,
$a2=ı^+2ȷ^+2k^b2=5i^+1j^+0k^$
Now,
$(a2a1)=2ı^+3ȷ^+2k^(b1×b2)=|ı^ȷ^k^231510|ı^+5ȷ^13k^(a2a1)(b1×b2)=(2ı^+3ȷ^+2k^)(ı^+5ȷ^13k^)9+15269$
We observe, (a2a1)(b1×b2)0
Thus, the given lines are not intersecting.

Straight Line in Space exercise 27.5 question 3(iv)

Answer: Given Lines are not interesting
Hint: Consider the given equation as (1) and (2)
Given:x54=y75=z+35(1) and x87=y71=z53(2)
Solution: Since line (1) passes through the point (5,7,3) and has direction ratios proportional to (4,5,5) its vector equation is γ=a1+λb1
Here,
$a1=5ı^+7ȷ^3k^b1=4ı^5ȷ^5k^$
Also line (2) passes through the point (8,7,5) and has direction ratios proportional to (7,1,3) its vector equation is γ=a2+μb2
Here,
$a2=8ı^+7ȷ^+5k^b2=7i^+1ȷ^+3k^$
Now,
$(a2a1)=3ı^+8k^(b1×b2)=|ı^ȷ^k^455713|10ı^47ȷ^+39k^(a2a1)(b1×b2)=(3ı^+8k^)(10ı^47ȷ^+39k^)30+312282$
We observe, (a2a1)(b1×b2)0
Thus, the given lines are not intersecting.

Straight Line in Space exercise 27.5 question 4(i)

Answer: d=26 units 
Hint: Let in L2 these is λ draw ∣∣ Line

Given: γ=(1ı^+2ȷ^+3k^)+λ(1ı^1ȷ^+k^) and γ=(2ı^ȷ^k^)+μ(ı^+ȷ^k^)
Solution:
$L1(1,2,3),x11=y21=z31L2(2,1,1),x21=y+11=z+11=λ$
Line (2) becomes (λ+2,λ1,λ1)
$=(λ+21)ı^+(λ12)ȷ^+(λ13)k^=(λ+1)ı^+(λ3)ȷ^+(λ4)k^$
$=(λ+1)(1)+(λ3)(1)+(λ4)(1)=λ+1+λ+3+λ4=3λ=0$
λ=0
The shortest distance between the ∣∣ Line is 2,1,1and(1,2,3)

Straight Line in Space exercise 27.5 question 4(ii)

Answer: d=0
Hint:Using the equation d=|(a2a1)(b1×b2)||(b1×b2)| Let the given lines L1 and L2
Given: γ=(ı^+ȷ^)+λ(2ı^ȷ^+k^) and γ=(2ı^+ȷ^k^)+μ(4ı^2ȷ^+2k^)
Solution:
$L1=a1+λb1 and L2=a2+μb2(b1×b2)=|ı^ȷ^k^211422|ı^(0)ȷ^(0)+k^(b1×b2)=0$
So the shortest distance is =0

Straight Line in Space exercise 27.5 question 5(i)

Answer: d=0

Hint: xx1x2x1=yy1y2y1=zz1z2z1

Given: (0,0,0) and (1,0,2)
Solution:
Applying the given point in the formula of the straight line
$x010=y000=z021x1=y0=z2$
Solution (ii)
Again applying the points(1,3,0) and (0,3,0)
The equation of the line passing through the points (1,3,0) is,
$x101=y333=z021x11=y30=z0$
Since the first line passes through the points (1,3,0) and has the directions proportional to (1,0,2) its vector is,
γ=a1+λb1(1)
Hence,
$a=0ı^+0ȷ^+0k^b=i^+0ȷ^+2k^$
Also, the second line passes through the point (1,3,0) and has the directions ratios proportional to (1,0,0) its vector is,
γ=a2+μb2 (2) 
Here,
$a2=ı^+3j^+0k^b2=ı^+0ȷ^+0k^$
Now,
$(a2a1)=ı^+3ȷ^+0k^(b1×b2)=|ı^ȷ^k^102100|0ı^2ȷ^+0k^$
$|b1×b2|=0+4+02|(a2a1)(b1×b2)|=|(ı^+3ȷ^+0k^)(0ı^2ȷ^+0k^)|$
The shortest distance between the lines,
$γ=a1+λb1γ=a2+μb2$
$d=|(a2a1)(b1×b2)||(b1×b2)|d=|6||2|d=3$

Straight Line in Space exercise 27.5 question 5(ii)

Answer: d=0

Hint: xx1x2x1=yy1y2y1=zz1z2z1

Given: (0,0,0) and (1,0,2)
Solution:
Applying the given point in the formula of the straight line
$x010=y000=z021x1=y0=z2$
Solution (ii)
Again applying the points(1,3,0) and (0,3,0)
The equation of the line passing through the points (1,3,0) is,
$x101=y333=z021x11=y30=z0$
Since the first line passes through the points (1,3,0) and has the directions proportional to (1,0,2) its vector is,
γ=a1+λb1(1)
Hence,
$a=0ı^+0ȷ^+0k^b=i^+0ȷ^+2k^$
Also, the second line passes through the point (1,3,0) and has the directions ratios proportional to (1,0,0) its vector is,
γ=a2+μb2 (2) 
Here,
$a2=ı^+3j^+0k^b2=ı^+0ȷ^+0k^$
Now,
$(a2a1)=ı^+3ȷ^+0k^(b1×b2)=|ı^ȷ^k^102100|0ı^2ȷ^+0k^$
$|b1×b2|=0+4+02|(a2a1)(b1×b2)|=|(ı^+3ȷ^+0k^)(0ı^2ȷ^+0k^)|$
The shortest distance between the lines,
$γ=a1+λb1γ=a2+μb2$
$d=|(a2a1)(b1×b2)||(b1×b2)|d=|6||2|d=3$

Straight Line in Space exercise 27.5 question 6

Answer: a1=ı^+2ȷ^+4k^,b1=2ı^3ȷ^6k^
a2=3ı^+3ȷ^5k^b2=4ı^+6ȷ^+12k^ and d=2937 units 

Hint: using expression |a2a1)×b1b|

Given: x12=y23=z+46 and x34=y36=Z+512

Solution:
Let line x1/2=y23=z+y6=μ ………… (i)
From above point (x,y,z) on line 1 will be(2μ+1,3μ+2,6μ4)
Let line 2 x3/4=y36=z+512=λ ...............(ii)
From above point (x,y,z) on line 2 will be (4λ+3,6λ+3,12λ5)
Position vector from equation (i) we get
$8=(2μ+1)ı^+(3μ+2)ȷ^+(6μ4)k^=(ı^+2ȷ^4k^)+(2ı^+3ȷ^+6k^)a1=ı^+2ȷ^4k^,b1=2ı^+3ȷ^+6k^$
Position vector from evaluation (ii) we get
$8=(4λ+3)ı^+(6λ+3)ȷ^+(12λ5)k^=(3ı^+3ȷ^5k^)+λ(4ı^+6ȷ^+12k^a2)=3ı^+3ȷ^5k^,b2=4ı^+6ȷ^+12k^$
 From b1 and b2 we get b2=2b1
Shortest Distance =|a2a1)×b1b|
(a2a1)=(3i^+3j^5k^)(i^+2ȷ^4k^=2i^+j^k^
(a2a1)xb $=\left|i^j^k^211236\right|=9 \hat{i}-14 \hat{\jmath}+4 \widehat{k}$
$(a2a1)×b=19)2+(14)2(4)2=81+196+16=293|b|=22+32+62=4+9+36=7$
Shortest distance =2937 units

Straight Line in Space exercise 27.5 question 7(i)

Answer: shortest distance =32
Hints: using expression D=|(a2a1)(b1×b2)(b1×b2)|
Given:8=ı^+2ȷ^+k^+λ(ı^ȷ^+k^) and 8=2ı^ȷ^k^+μ(2ı^+ȷ^+2k^)
Solution:
$a1=ı^+2ȷ^+k^,b1=ı^ȷ^k^a2=2ı^ȷ^k^b2=2ı^+ȷ^+2k^a2a1=ı^3ȷ^2k^$
$\overrightarrow{b_{1}}-\overrightarrow{b_{2}}=\left|ı^ȷ^k^111212\right|$
$=ı^(3)ȷ^(0)+k^(1+2)=3ı^+3k^SD=(2i^j^k^)(3i^+3k^)9+9$
$=|6318|=932=32 units $

Straight Line in Space exercise 27.5 question 7(ii)

Answer: d=229 units 
Hint: using expression $\left|x2x1y2y1z2z1a1b1c1a2b2c2\right|$
(b1c2b2c1)2+(c1a2c2a1)2+(a1b2+a2b1)2
Given: x+17=y+16=z+11 and x31=y52=z71
Solution:
It is known that the shortest distance between the two lines,
xx1a1=yy1b1=zz1c1 and xx2a2=yy2b2=zz2c2
Comparing the given equation we get,
$x1=1,y1=1,z1=1a1=7,b1=6,c1=1x2=3,y2=5,z2=7a2=1,b2=2,c2=1$
Then
$|x2x1y2y1z2z1a1b1c1a2b2c2|=|468761121|=4(6+2)6(71)+8(14+6)=116$
$b1c2b2c1)2+(c1a2c2a2)2+(a1b2a2b1)2=(6+2)2+(1+7)2+(14+6)2=16+36+64$
$=116=229$
Substituting all the values in equation we get
d=116229=5829=2×2929=229
Since the distance is always non-negative the distance between the given line is
=229 units 

Straight Line in Space exercise 27.5 question 7(iii)

Answer: d=|319|
Hint: using (b1×b2)(a2a1)(b1×b2)
Given: 8=ı^+2ȷ^+3k^+λ(ı^3ȷ^+2k^)and
8=4ı^+5ȷ^+6k^+μ(2ı^+3ȷ^+k^)
Solution:
Shortest distance between the lines with vector equations
8=a1+b1 and 8=a2+b2 is |(b1×b2)(b1×a2a1)|
Now
8=ı^+2ȷ^+3k^+λ(ı^3ȷ^+2k^) 8=(4ı^+5ȷ^+6k^+μ(2ı^+3ȷ^+k^)
Comparing with 8=a1+λb1 Comparing with 8=a2+μb2
a1=i^+2j^+3k^ a2=4i^+5j^+6k^
and and
b1=i^3j^+2k^ b2=2i^3j^+1k^

$(a2a1)=(4ı^+5ȷ^+6k^(1ı^+2ȷ^+3k^)=(41)ı^+(52)ȷ^+(63)k^=3ı^+3ȷ^+3k^$
$\overrightarrow{\left(b_{1}\right.} x \overrightarrow{\left.b_{2}\right)}=\left|ı^ȷ^k^132231\right|$
$=ı^[(3×1)(3×2)]ȷ^[(1×1)(2×2)]+k^[(1×3)(2×3)]=ı^(9)ȷ^(3)+k^(9)=9ı^+3ȷ^+9k^$
Magnitude of (b1×b2)=(9)2+32+92
$=81+9+81=171$
$=9×29=319$
Also
$(b1×b2)(a2a1)=(9(+3ȷ^+9k^)(3ı^+3ȷ^+3k^)=(9×3)+(3×3)+(9+3)=27+9+27=9$
Shortest Distance $=|9319|$
=|319|

Straight Line in Space exercise 27.5 question 7(iv)

Answer: d=9
Hint: using the expression d=|(a2a1)(b1×b2)||(b1×b2)|
Given:

$8=6ı^+2ȷ^+2k^+λ(ı^2ȷ^+2k^) and 8=4ı^k^+\boldsymbolμ(2ı^+3ȷ^+k^)$

Solution:
$a1=6ı^+2ȷ^+2k^a2=4ı^k^b1=ı^2ȷ^+2k^$
$b2=3^l2ȷ^2k^a2a1=10ı^2ȷ^+3k^$
$\text { and } \overrightarrow{b_{1}} \times \overrightarrow{b_{2}}=\left|ı^ȷ^k^122322\right| \Rightarrow 8 \hat{\imath}+8 \hat{\jmath}+4 \hat{k}$
$|b1×b2|82+82+4264+64+16=14412$
and
$(a2a1)(b1×b2)=10ı^2ȷ^+3k^(8ı^+8ȷ^+4k^)=801612=108$
The shortest distance between the lines
$8=a1+λb1 and 8=a2+μb2 d=|10812|=9$

Straight Line in Space exercise 27.5 question 8

Answer: D=17
Hint: using formula distance between line|(a2a1)bb|
Given: 8=ı^+2ȷ^4k^++λ(2ı^3ȷ^+6k^) and 
8=3ı^+3ȷ^5k^+μ(2ı^+3ȷ^+6k^)
Solution:
By the given formula,
$=|(2ı^+ȷ^k^)(2i^+3j^+6k^)4+9+36|=4+3649$
$=4+367=1/7$

Straight Line in Space exercise 27.5 question 9

Answer: d=5807 units 
Hint: find l2 by the given points.
Given: 8=(2ı^+3ȷ^)+λ(2ı^3ȷ^+6k^), point (2,3,2)
Solution:
Evaluation of line passing through (2,3,2)and parallel to 2 is given by
L2=(2ı^+3ȷ^+2k^)+μ(2ı^3ȷ^+6k^)
Now,
(a2a1)=(μı^+2k^)
and 5=(2ı^3ȷ^+6k^)
Now,
$\left(\overrightarrow{a_{2}}-\overrightarrow{a_{1}}\right) x \overrightarrow{b_{2}}=\left|ı^ȷ^k^402236\right| \quad 6 \hat{\imath}-20 \hat{\jmath}+12 \hat{k}$
Hence the revised distance is
(a2a1)×b(b)=36+400+1444+9+36
=5807 units 


The RD Sharma Class 12 Solution of Straight Line in Space exercise 27.5 is used by thousands of students and teachers for the practical knowledge of maths. The RD Sharma class 12th exercise 27.5 consists of 27 questions covering concepts like shortest distance between pairs of lines in vector and cartesian form of the equation, vector equation of a line passing through the point, and parallel to the bar.

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