#### Chapters

Chapter 2: Relations and Functions

Chapter 3: Trigonometric Functions

Chapter 4: Principle of Mathematical Induction

Chapter 5: Complex Numbers and Quadratic Equations

Chapter 6: Linear Inequalities

Chapter 7: Permutations and Combinations

Chapter 8: Binomial Theorem

Chapter 9: Sequences and Series

Chapter 10: Straight Lines

Chapter 11: Conic Sections

Chapter 12: Introduction to Three Dimensional Geometry

Chapter 13: Limits and Derivatives

Chapter 14: Mathematical Reasoning

Chapter 15: Statistics

Chapter 16: Probability

#### NCERT Mathematics Class 11

## Chapter 10: Straight Lines

#### Chapter 10: Straight Lines solutions [Pages 211 - 212]

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

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

Find the distance between P (x_{1}, y_{1}) and Q (x_{2}, y_{2}) when : (i) PQ is parallel to the y-axis, (ii) PQ is parallel to the x-axis

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

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

Find the slope of the line, which makes an angle of 30° with the positive direction of *y*-axis measured anticlockwise.

Find the value of *x* for which the points (*x*, –1), (2, 1) and (4, 5) are collinear.

Without using distance formula, show that points (–2, –1), (4, 0), (3, 3) and (–3, 2) are vertices of a parallelogram.

Find the angle between the *x*-axis and the line joining the points (3, –1) and (4, –2).

The slope of a line is double of the slope of another line. If tangent of the angle between them is `1/3`, find the slopes of the lines

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}).

If three point (*h,* 0), (*a, b*) and (0*, k*) lie on a line, show that `q/h + b/k = 1`

Consider the given population and year graph. Find the slope of the line AB and using it, find what will be the population in the year 2010?

#### Chapter 10: Straight Lines solutions [Pages 219 - 220]

Write the equations for the *x* and *y*-axes.

Find the equation of the line which passes through the point (–4, 3) with slope `1/2`

Find the equation of the line which passes though (0, 0) with slope *m*.

Find the equation of the line which passes though `(2, 2sqrt3)` and is inclined with the *x*-axis at an angle of 75°

Find the equation of the line which intersects the *x*-axis at a distance of 3 units to the left of origin with slope –2.

Find the equation of the line which intersects the *y*-axis at a distance of 2 units above the origin and makes an angle of 30° with the positive direction of the *x*-axis.

Find the equation of the line which passes through the points (–1, 1) and (2, –4).

Find the equation of the line which is at a perpendicular distance of 5 units from the origin and the angle made by the perpendicular with the positive* x*-axis is 30°

The vertices of ΔPQR are P (2, 1), Q (–2, 3) and R (4, 5). Find equation of the median through the vertex R.

The vertices of ΔPQR are P (2, 1), Q (–2, 3) and R (4, 5). Find equation of the median through the vertex R.

Find the equation of the line passing through (–3, 5) and perpendicular to the line through the points (2, 5) and (–3, 6).

A line perpendicular to the line segment joining the points (1, 0) and (2, 3) divides it in the ratio 1:*n*. Find the equation of the line.

Find the equation of a line that cuts off equal intercepts on the coordinate axes and passes through the point (2, 3).

Find equation of the line passing through the point (2, 2) and cutting off intercepts on the axes whose sum is 9.

Find equation of the line through the point (0, 2) making an angle `(2pi)/3` with the positive *x*-axis. Also, find the equation of line parallel to it and crossing the *y*-axis at a distance of 2 units below the origin.

The perpendicular from the origin to a line meets it at the point (– 2, 9), find the equation of the line.

The length L (in centimetre) of a copper rod is a linear function of its Celsius temperature C. In an experiment, if L = 124.942 when C = 20 and L = 125.134 when C = 110, express L in terms of C

The owner of a milk store finds that, he can sell 980 litres of milk each week at Rs 14/litre and 1220 litres of milk each week at Rs 16/litre. Assuming a linear relationship between selling price and demand, how many litres could he sell weekly at Rs 17/litre?

P (*a, b*) is the mid-point of a line segment between axes. Show that equation of the line is `x/a + y/b = 2`

Point R (*h, k*) divides a line segment between the axes in the ratio 1:2. Find equation of the line.

By using the concept of equation of a line, prove that the three points (3, 0), (–2, –2) and (8, 2) are collinear.

#### Chapter 10: Straight Lines solutions [Pages 227 - 228]

Reduce the following equations into slope-intercept form and find their slopes and the *y*-intercepts.

(i) *x *+ 7*y *= 0

(ii) 6*x *+ 3*y *– 5 = 0

(iii) *y *= 0

Reduce the following equations into intercept form and find their intercepts on the axes.

(i) 3*x *+ 2*y *– 12 = 0

(ii) 4*x *– 3*y *= 6

(iii) 3*y *+ 2 = 0

Reduce the following equations into normal form. Find their perpendicular distances from the origin and angle between perpendicular and the positive *x*-axis.

i) `x – sqrt3y + 8 = 0`

(ii) *y *– 2 = 0

(iii) *x *– *y *= 4

Find the distance of the point (–1, 1) from the line 12(*x *+ 6) = 5(*y *– 2).

Find the points on the *x*-axis, whose distances from the `x/3 +y/4 = 1` are 4 units.

Find the distance between parallel lines 15*x *+ 8*y *– 34 = 0 and 15*x *+ 8*y *+ 31 = 0

Find the distance between parallel lines *l *(*x *+ *y*) + *p *= 0 and *l *(*x *+ *y*) – *r *= 0

Find equation of the line parallel to the line 3*x *– 4*y* + 2 = 0 and passing through the point (–2, 3).

Find equation of the line perpendicular to the line *x *– 7*y *+ 5 = 0 and having *x *intercept 3.

Find angles between the lines `sqrt3x + y = 1 and x + sqrt3y = 1`

The line through the points (*h*, 3) and (4, 1) intersects the line 7*x* – 9*y* – 19 = 0*. *at right angle. Find the value of *h*.

Prove that the line through the point (*x*_{1}, *y*_{1}) and parallel to the line A*x + *B*y + *C = 0 is A (*x –x*_{1}) *+ *B (*y – y*_{1}) = 0.

Two lines passing through the point (2, 3) intersects each other at an angle of 60°. If slope of one line is 2, find equation of the other line.

Find the equation of the right bisector of the line segment joining the points (3, 4) and (*–*1, 2).

Find the coordinates of the foot of perpendicular from the point (*–*1, 3) to the line 3*x *– 4*y *– 16 = 0.

The perpendicular from the origin to the line *y = mx + c *meets it at the point (*–*1, 2). Find the values of *m *and *c*.

If *p *and *q *are the lengths of perpendiculars from the origin to the lines *x *cos *θ* – *y *sin *θ* = *k *cos 2*θ* and *x*sec *θ*+ *y *cosec *θ* = *k*, respectively, prove that *p*^{2} + 4*q*^{2} = *k*^{2}

In the triangle ABC with vertices A (2, 3), B (4, *–*1) and C (1, 2), find the equation and length of altitude from the vertex A.

If *p *is the length of perpendicular from the origin to the line whose intercepts on the axes are *a *and *b*, then show that `1/p^2 = 1/a^2 + 1/b^2`

#### Chapter 10: Straight Lines solutions [Pages 233 - 234]

Find the values of k for which the line (k–3) x – (4 – k^{2}) y + k^{2} –7k + 6 = 0 is

(a) Parallel to the *x*-axis,

(b) Parallel to the *y*-axis,

(c) Passing through the origin.

Find the values of q and p, if the equation x cos q + y sinq = p is the normal form of the line `sqrt3 x` + y + 2 = 0.

Find the equations of the lines, which cut-off intercepts on the axes whose sum and product are 1 and –6, respectively.

What are the points on the *y*-axis whose distance from the line `x/3 + y/4 = 1` is 4 units

Find perpendicular distance from the origin to the line joining the points (cosΘ, sin Θ) and (cosΦ, sin Φ).

Find the equation of the line parallel to *y*-axis and drawn through the point of intersection of the lines *x*– 7*y* + 5 = 0 and 3*x* + *y* = 0.

Find the equation of a line drawn perpendicular to the line `x/4 + y/6 = 1`through the point, where it meets the *y*-axis.

Find the area of the triangle formed by the lines *y* –* x *= 0, *x* + *y* = 0 and *x* – *k* = 0.

Find the value of *p* so that the three lines 3*x* + *y* – 2 = 0, *px* + 2*y* – 3 = 0 and 2*x* – *y* – 3 = 0 may intersect at one point.

If three lines whose equations are y = m_{1}x + c_{1}, y = m_{2}x + c_{2} and y = m_{3}x + c_{3} are concurrent, then show that m_{1}(c_{2} – c_{3}) + m_{2} (c_{3} – c1) + m_{3} (c_{1} – c_{2}) = 0.

Find the equation of the lines through the point (3, 2) which make an angle of 45° with the line *x* –2*y* = 3.

Find the equation of the line passing through the point of intersection of the lines 4*x* + 7*y* – 3 = 0 and 2*x*– 3*y* + 1 = 0 that has equal intercepts on the axes.

Show that the equation of the line passing through the origin and making an angle *θ *with the line `y = mx + c " is " y/c = (m+- tan theta)/(1 +- m tan theta)`

In what ratio, the line joining (–1, 1) and (5, 7) is divided by the line *x* + *y* = 4?

Find the distance of the line 4*x* + 7*y* + 5 = 0 from the point (1, 2) along the line 2*x* – *y* = 0.

Find the direction in which a straight line must be drawn through the point (–1, 2) so that its point of intersection with the line *x* + *y* = 4 may be at a distance of 3 units from this point.

The hypotenuse of a right angled triangle has its ends at the points (1, 3) and (−4, 1). Find the equation of the legs (perpendicular sides) of the triangle.

Find the image of the point (3, 8) with respect to the line *x* + 3*y* = 7 assuming the line to be a plane mirror.

If the lines *y* = 3*x* + 1 and 2*y* = *x* + 3 are equally inclined to the line *y* = *mx* + 4, find the value of *m*.

If sum of the perpendicular distances of a variable point P (*x*,* y*) from the lines *x* + *y* – 5 = 0 and 3*x* – 2*y*+ 7 = 0 is always 10. Show that P must move on a line.

Find equation of the line which is equidistant from parallel lines 9*x *+ 6*y* – 7 = 0 and 3*x* + 2*y* + 6 = 0.

A ray of light passing through the point (1, 2) reflects on the *x*-axis at point A and the reflected ray passes through the point (5, 3). Find the coordinates of A.

Prove that the product of the lengths of the perpendiculars drawn from the points

`(sqrt(a^2 - b^2),0)` and `(-sqrta^2-b^2,0)` to the line `x/a cos theta + y/b sin theta = 1` is `b^2`

A person standing at the junction (crossing) of two straight paths represented by the equations 2*x* – 3*y*+ 4 = 0 and 3*x* + 4*y* – 5 = 0 wants to reach the path whose equation is 6*x* – 7*y* + 8 = 0 in the least time. Find equation of the path that he should follow.

#### Chapter 10: Straight Lines solutions [Page 211]

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).

## Chapter 10: Straight Lines

#### NCERT Mathematics Class 11

#### Textbook solutions for Class 11

## NCERT solutions for Class 11 Mathematics chapter 10 - Straight Lines

NCERT solutions for Class 11 Maths chapter 10 (Straight Lines) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Mathematics Textbook for Class 11 solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 11 Mathematics chapter 10 Straight Lines are Equation of Family of Lines Passing Through the Point of Intersection of Two Lines, Shifting of Origin, Brief Recall of Two Dimensional Geometry from Earlier Classes, Distance of a Point from a Line, General Equation of a Line, Various Forms of the Equation of a Line, Slope of a Line.

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