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NCERT Solutions for Exercise 10.1 Class 11 Maths Chapter 10 - Straight Lines

NCERT Solutions for Exercise 10.1 Class 11 Maths Chapter 10 - Straight Lines

Edited By Vishal kumar | Updated on Nov 27, 2023 01:34 PM IST

NCERT Solutions for Class 11 Maths Chapter 10: Straight Lines Exercise 10.1- Download Free PDF

NCERT Solutions for Exercise 10.1 Class 11 Maths Chapter 10 Straight Lines are discussed here. These NCERT solutions are created by subject matter expert at Careers360 considering the latest syllabus and pattern of CBSE 2023-24. In the earlier classes, you have already learned about the basics of two-dimensional coordinate geometry like the distance between two points, section formulae, coordinate axes, coordinate plane, plotting of points in a plane, etc. In the NCERT solutions for Class 11 maths ex 10.1, you will learn about the basic coordinate geometry like measuring the slope of the line when the coordinates of any two points on the line are given, conditions for parallelism and perpendicularity of lines in terms of their slopes, angle between two lines, colinearity of three points, etc.

NCERT solutions for exercise 10.1 Class 11 Maths chapter 10 Straight Lines focuses straight line where you learn about the slope of lines, the angle between two lines. 11th class Maths exercise 10.1 answers are designed as per the students demand covering comprehensive, step by step solutions of every problem. Practice these questions and answers to command the concepts, boost confidence and in depth understanding of concepts. Students can find all exercise together using the link provided below.

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**As per the CBSE Syllabus for 2023-24, this chapter has been renumbered as Chapter 9.

NCERT Solutions for Class 11 Maths Chapter 10 – Straight Lines Exercise 10.1

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Access Straight Lines Class 11 Chapter 10 Exercise 10.1

Question:1 Draw a quadrilateral in the Cartesian plane, whose vertices are (-4,5),(0,7),(5,-5) and (-4,-2). Also, find its area.

Answer:



Area of ABCD = Area of ABC + Area of ACD
Now, we know that the area of a triangle with vertices (x_1,y_1),(x_2,y_2) \ and \ (x_3,y_3) is given by
A = \frac{1}{2}|x_1(y_2-y_3)+x_2(y_3-y_1)+x_3(y_1-y_2)|
Therefore,
Area of triangle ABC = \frac{1}{2}|-4(7+5)+0(-5-5)+5(5-7)|= \frac{1}{2}|-48-10|= \frac{58}{2}=29
Similarly,
Area of triangle ACD = \frac{1}{2}|-4(-5+2)+5(-2-5)+-4(5+5)|= \frac{1}{2}|12-35-40|= \frac{63}{2}
Now,
Area of ABCD = Area of ABC + Area of ACD
=\frac{121}{2} \ units

Question:2 The base of an equilateral triangle with side 2a lies along the y-axis such that the mid-point of the base is at the origin. Find vertices of the triangle.

Answer:


it is given that it is an equilateral triangle and length of all sides is 2a
The base of the triangle lies on y-axis such origin is the midpoint
Therefore,
Coordinates of point A and B are (0,a) \ \ and \ \ (0,-a) respectively
Now,
Apply Pythagoras theorem in triangle AOC
AC^2=OA^2+OC^2
(2a)^2=a^2+OC^2
OC^2= 4a^2-a^2=3a^2
OC=\pm \sqrt3 a
Therefore, coordinates of vertices of the triangle are
(0,a),(0,-a) \& \ (\sqrt3a,0) \ \ or \ \ (0,a),(0,-a) \& \ (-\sqrt3a,0)

Question:3(i) Find the distance between P(x_1,y_1) and Q(x_2,y_2) when :

PQ is parallel to the y-axis.

Answer:

When PQ is parallel to the y-axis
then, x coordinates are equal i.e. x_2 = x_1
Now, we know that the distance between two points is given by
D = |\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}|
Now, in this case x_2 = x_1
Therefore,
D = |\sqrt{(x_2-x_2)^2+(y_2-y_1)^2}| = |\sqrt{(y_2-y_1)^2}|= |(y_2-y_1)|
Therefore, the distance between P(x_1,y_1) and Q(x_2,y_2) when PQ is parallel to y-axis is |(y_2-y_1)|

Question:3(ii) Find the distance between P(x_1,y_1) and Q(x_2,y_2) when :

PQ is parallel to the x-axis.

Answer:

When PQ is parallel to the x-axis
then, x coordinates are equal i.e. y_2 = y_1
Now, we know that the distance between two points is given by
D = |\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}|
Now, in this case y_2 = y_1
Therefore,
D = |\sqrt{(x_2-x_1)^2+(y_2-y_2)^2}| = |\sqrt{(x_2-x_1)^2}|= |x_2-x_1|
Therefore, the distance between P(x_1,y_1) and Q(x_2,y_2) when PQ is parallel to the x-axis is |x_2-x_1|

Question:4 Find a point on the x-axis, which is equidistant from the points (7,6) and (3,4).

Answer:

Point is on the x-axis, therefore, y coordinate is 0
Let's assume the point is (x, 0)
Now, it is given that the given point (x, 0) is equidistance from point (7, 6) and (3, 4)
We know that
Distance between two points is given by
D = |\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}|
Now,
D_1 = |\sqrt{(x-7)^2+(0-6)^2}|= |\sqrt{x^2+49-14x+36}|= |\sqrt{x^2-14x+85}|
and
D_2 = |\sqrt{(x-3)^2+(0-4)^2}|= |\sqrt{x^2+9-6x+16}|= |\sqrt{x^2-6x+25}|
Now, according to the given condition
D_1=D_2
|\sqrt{x^2-14x+85}|= |\sqrt{x^2-6x+25}|
Squaring both the sides
x^2-14x+85= x^2-6x+25\\ 8x = 60\\ x=\frac{60}{8}= \frac{15}{2}
Therefore, the point is ( \frac{15}{2},0)

Question:5 Find the slope of a line, which passes through the origin, and the mid-point of the line segment joining the points P(0,-4) and B(8,0).

Answer:

Mid-point of the line joining the points P(0,-4) and B(8,0). is
l = \left ( \frac{8}{2},\frac{-4}{2} \right ) = (4,-2)
It is given that line also passes through origin which means passes through the point (0, 0)
Now, we have two points on the line so we can now find the slope of a line by using formula
m = \frac{y_2-y_1}{x_2-x_1}
m = \frac{-2-0}{4-0} = \frac{-2}{4}= \frac{-1}{2}
Therefore, the slope of the line is \frac{-1}{2}

Question:6 Without using the Pythagoras theorem, show that the points (4,4),(3,5) and (-1,-1), are the vertices of a right angled triangle.

Answer:

It is given that point A(4,4) , B(3,5) and C(-1,-1) are the vertices of a right-angled triangle
Now,
We know that the distance between two points is given by
D = |\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}|
Length of AB = |\sqrt{(4-3)^2+(4-5)^2}|= |\sqrt{1+1}|= \sqrt2
Length of BC = |\sqrt{(3+1)^2+(5+1)^2}|= |\sqrt{16+36}|= \sqrt{52}
Length of AC = |\sqrt{(4+1)^2+(4+1)^2}|= |\sqrt{25+25}|= \sqrt{50}
Now, we know that Pythagoras theorem is
H^2= B^2+L^2
Is clear that
(\sqrt{52})^2=(\sqrt{50})^2+(\sqrt 2)^2\\ 52 = 52\\ i.e\\ BC^2= AB^2+AC^2
Hence proved

Question:7 Find the slope of the line, which makes an angle of 30^{\circ} with the positive direction of y-axis measured anticlockwise.

Answer:

It is given that the line makes an angle of 30^{\circ} with the positive direction of y-axis measured anticlockwise
Now, we know that
m = \tan \theta
line makes an angle of 30^{\circ} with the positive direction of y-axis
Therefore, the angle made by line with the positive x-axis is = 90^{\degree}+30^{\degree}= 120\degree
Now,
m = \tan 120\degree = -\tan 60\degree = -\sqrt3
Therefore, the slope of the line is -\sqrt3

Question:8 Find the value of x for which the points (x,-1),(2,1) and (4,5) are collinear.

Answer:

Point is collinear which means they lie on the same line by this we can say that their slopes are equal
Given points are A(x,-1) , B(2,1) and C(4,5)
Slope = m = \frac{y_2-y_1}{x_2-x_1}
Now,
The slope of AB = Slope of BC
\frac{1+1}{2-x}= \frac{5-1}{4-2}
\frac{2}{2-x}= \frac{4}{2}\\ \\ \frac{2}{2-x} = 2\\ \\ 2=2(2-x)\\ 2=4-2x\\ -2x = -2\\ x = 1
Therefore, the value of x is 1

Question:9 Without using the distance formula, show that points (-2,-1),(4,0),(3,3) and (-3,2) are the vertices of a parallelogram.

Answer:

Given points are A(-2,-1),B(4,0),C(3,3) and D(-3,2)
We know the pair of the opposite side are parallel to each other in a parallelogram
Which means their slopes are also equal
Slope = m = \frac{y_2-y_1}{x_2-x_1}
The slope of AB =

\frac{0+1}{4+2} = \frac{1}{6}

The slope of BC =

\frac{3-0}{3-4} = \frac{3}{-1} = -3

The slope of CD =

\frac{2-3}{-3-3} = \frac{-1}{-6} = \frac{1}{6}

The slope of AD

= \frac{2+1}{-3+2} = \frac{3}{-1} = -3
We can clearly see that
The slope of AB = Slope of CD (which means they are parallel)
and
The slope of BC = Slope of AD (which means they are parallel)
Hence pair of opposite sides are parallel to each other
Therefore, we can say that points (-2,-1),(4,0),(3,3) and (-3,2) are the vertices of a parallelogram

Question:10 Find the angle between the x-axis and the line joining the points (3,-1) and (4,-2).

Answer:

We know that
m = \tan \theta
So, we need to find the slope of line joining points (3,-1) and (4,-2)
Now,
m = \frac{y_2-y_1}{x_2-x_1}= \frac{-2+1}{4-3} = -1
\tan \theta = -1
\tan \theta = \tan \frac{3\pi}{4} = \tan 135\degree
\theta = \frac{3\pi}{4} = 135\degree
Therefore, angle made by line with positive x-axis when measure in anti-clockwise direction is 135\degree

Question:11 The slope of a line is double of the slope of another line. If tangent of the angle between them is \frac{1}{3}, find the slopes of the lines

Answer:

Let m_1 \ and \ m_2 are the slopes of lines and \theta is the angle between them
Then, we know that
\tan \theta = \left | \frac{m_2-m_1}{1+m_1m_2} \right |
It is given that m_2 = 2m_1 and

\tan \theta = \frac{1}{3}
Now,
\frac{1}{3}= \left | \frac{2m_1-m_1}{1+m_1.2m_1} \right |
\frac{1}{3}= \left | \frac{m_1}{1+2m^2_1} \right |
Now,
3|m_1|= 1+2|m^2_1|\\ 2|m^2_1|-3|m_1|+ 1 = 0\\ 2|m^2_1|-2|m_1|-|m_1|+1=0\\ (2|m_1|-1)(|m_1|-1)= 0\\ |m_1|= \frac{1}{2} \ \ \ \ \ or \ \ \ \ \ \ |m_1| = 1
Now,
m_1 = \frac{1}{2} \ or \ \frac{-1}{2} \ or \ 1 \ or \ -1
According to which value of m_2 = 1 \ or \ -1 \ or \ 2 \ or \ -2
Therefore, m_1,m_2 = \frac{1}{2},1 \ or \ \frac{-1}{2},-1 \ or \ 1,2 \ or \ -1,-2

Question:12 A line passes through (x_1,y_1) and (h,k) . If slope of the line is m, show that k-y_1=m(h-x_1).

Answer:

Given that A line passes through (x_1,y_1) and (h,k) and slope of the line is m
Now,
m = \frac{y_2-y_1}{x_2-x_1}
\Rightarrow m = \frac{k-y_1}{h-x_1}
\Rightarrow (k-y_1)= m(h-x_1)
Hence proved

Question:13 If three points (h,0),(a,b) and (0,k) lie on a line, show that \frac{a}{h}+\frac{b}{k}=1.

Answer:

Points A(h,0),B(a,b) and C(0,k) lie on a line so by this we can say that their slopes are also equal
We know that
Slope = m = \frac{y_2-y_1}{x_2-x_1}

Slope of AB = \frac{b-0}{a-h} = \frac{b}{a-h}

Slope of AC = \frac{k-b}{0-a} = \frac{k-b}{-a}
Now,
Slope of AB = slope of AC
\frac{b}{a-h} = \frac{k-b}{-a}
-ab= (a-h)(k-b)
-ab= ak -ab-hk+hb\\ ak +hb = hk
Now divide both the sides by hk
\frac{ak}{hk}+\frac{hb}{hk}= \frac{hk}{hk}\\ \\ \frac{a}{h}+\frac{b}{k} = 1
Hence proved

Question:14 Consider the following population and year graph, find the slope of the line AB and using it, find what will be the population in the year 2010?

Answer:

Given point A(1985,92) and B(1995,97)
Now, we know that
Slope = m = \frac{y_2-y_1}{x_2-x_1}
m = \frac{97-92}{1995-1985} = \frac{5}{10}= \frac{1}{2}
Therefore, the slope of line AB is \frac{1}{2}
Now, the equation of the line passing through the point (1985,92) and with slope = \frac{1}{2} is given by
(y-92) = \frac{1}{2}(x-1985)\\ \\ 2y-184 = x-1985\\ x-2y = 1801
Now, in the year 2010 the population is
2010-2y = 1801\\ -2y = -209\\ y = 104.5
Therefore, the population in the year 2010 is 104.5 crore

More About NCERT Solutions for Class 11 Maths Chapter 10 Exercise 10.1:-

Class 11th Maths chapter 10 exercise 10.1 consists of basic questions related to coordinate geometry like finding the distance between two points, slope of a line given the coordinates of two points on the line, checking the colinearity of three points, etc. There are five solved examples and few properties related to a straight line are given before the Class 11 Maths chapter 10 exercise 10.1 in the NCERT textbook. You must go through these properties and definitions of straight lines before solving the NCERt syllabus exercise problems.

Also Read| Straight Lines Class 11 Notes

Benefits of NCERT Solutions for Class 11 Maths Chapter 10 Exercise 10.1:-

  • As exercise 10.1 Class 11 Maths is a quite basic exercise on two-coordinate geometry, you won't get much difficulty understanding this exercise.
  • Class 11 Maths chapter 10 exercise 10.1 solutions are here to help you to get conceptual clarity.
  • You can use Class 11th Maths chapter 10 exercise 10.1 solutions as a reference while solving the NCERT problems.
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Key Features of Exercise 10.1 Class 11 Maths Solutions

  1. Comprehensive Coverage: These 11th class maths exercise 10.1 answers cover all exercises and problems in Chapter 10.1 of the Class 11 Mathematics textbook.

  2. Step-by-Step Approach: Ex 10.1 class 11 are presented in a clear, step-by-step format for easy understanding and problem-solving.

  3. Clarity and Accuracy: The class 11 maths ex 10.1 solutions are precise and clear, ensuring a solid grasp of mathematical concepts and methods.

  4. Conceptual Understanding: They focus on deepening understanding rather than memorization, promoting critical thinking.

  5. Free Access: These class 11 ex 10.1 resources are typically available at no cost, making them accessible for self-study.

  6. Supplementary Learning Tool: They can complement classroom instruction and aid exam preparation.

  7. Homework and Practice: Useful for checking work, practicing problem-solving, and improving overall math skills.

Also see-

NCERT Solutions of Class 11 Subject Wise

Subject Wise NCERT Exampler Solutions

Happy learning!!!

Frequently Asked Questions (FAQs)

1. What is the inclination of a line 'l' ?

The angle made by line l with the positive direction of x-axis and measured anticlockwise is called the inclination of the line 'l'.

2. What is the slope of a line ?

The tan θ is called the slope or gradient of line 'l' where θ is the inclination of line 'l'.

3. If the inclination of line in 45 degree than what is the slope of the line ?

Slope of line = tan 45 = 1

4. Let ABC are three points on xy-plane, than what is the condition for collinearity of ABC ?

Condition for collinearity of points A, B, and C.

Slope of AB = Slope of BC

5. What is the slope of x-axis ?

The slope of the x-axis is zero.

6. What is the slope of y-axis ?

The slope of the y-axis is not defined.

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