Chapter 15: Introduction to Graphs

Q1Written answer

Plot the following points on a graph sheet. Verify if they lie on a line

(a) A(4,0), B(4, 2),C(4,6), D(4, 2.5)

(b) P(1, 1), Q(2, 2), R(3,3), S(4, 4)

(c) K(2, 3), L(5, 3), M(5,5), N(2, 5)

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Worked solution

Plot all the points on the graph.

Ncert solution class 8 chapter 15-11

(a) All points, A, B, C and D, lie on a vertical line.

(b) P,Q, R and S points also make a line. It verifies that these points lie on a line.

(c) Points K, L, M and N. These points do not lie in a straight line.

Q2Written answer

Draw the line passing through (2,3)and(3,2). Find the coordinates of the points at which this line meets the x-axis and y-axis.

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Worked solution

Graph for the line passes through points (2, 3) and (3, 2) is

Ncert solution class 8 chapter 15-12

The coordinates of the points at which this line meets the x-axis at (5, 0) and Y axis at (0,5).

Q3Written answer

Write the coordinates of the vertices of each of these adjoining figures.

Ncert solution class 8 chapter 15-13

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Worked solution

We can observe three figures named as, OABC, PQRS and LMK.

Vertices of figure OABC

O (0, 0), A (2, 0), B (2, 3) and C (0, 3)

Vertices of figure PQRS

P (4, 3), Q (6, 1), R (6, 5) and S (4, 7)

Vertices of figure LMK

L (7, 7), M(10, 8) and K(10,5)

Q4Written answer

State whether True or False. Correct those that are False.

(i) A point whose x-coordinate is zero and y-coordinate is non-zero will lie on the y-axis.

(ii) A point whose y-coordinate is zero and x-coordinate is 5 will lie on the y-axis.

(iii) The coordinates of the origin are (0, 0).

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Worked solution

i) True.

ii) False; it will lie on the x-axis.

(iii) True.

Exercise 15.2