Page 157 - Maths Skills - 7

Lines and Angles 155

9. Find the value of x in the following figures:

x
x
45° x 115° 65° 60°
(i) (ii) (iii)

100° x 100°
x x
x + 35° 100°
x – 50°

(iv) (v) (vi)
10. In the given figure, if ∠1 = 75°, then find the measure of the other angles.

PAIR OF LINES

Two lines can either intersect or remain non-intersecting as shown below:

Thus, they can either be intersecting lines or parallel lines.

Intersecting Lines m
Two lines are said to be intersecting if they have a point in common. The common point
is called the point of intersection. For example, line l and m are intersecting lines with ‘O’ O
as their point of intersection.
l
Parallel Lines

We have already learnt that parallel lines are those lines which never meet. The distinct characteristic of parallel
lines is that the perpendicular distance between them is same everywhere.
P Q
For example; If two lines PQ and RS are parallel, then we write PQ || RS. In Fig. PQ

and RS are two parallel lines. R S

Transversals
A line which cuts two or more lines in a plane at different A A I B
points is called a transversal as shown in Figs. 1 and 2. E B C J D
The given lines may be parallel or non-parallel. E K F

C F G
D L H
Fig. 1 Fig. 2