# Lines And Angles | NCERT Class 7 Maths Chapter 5 Solutions

Basic Facts:

A line-segment has two end points.

A ray has only one end point (its vertex).

A line has no end points on either side.

An angle is formed when two lines (or rays or line-segments) meet.

When the sum of the measures of two angles is 90 degree, the angles are called complementary angles.

When the sum of the measures of two angles is 180 degree, the angles are called supplementary angles.

A linear pair is a pair of adjacent angles whose non-common sides are opposite rays.

When two lines l and m meet, we say they intersect: the meeting point is called the point of intersection.

When lines drawn on a sheet of paper do not meet, however far produced, we call them to be parallel lines.

When two lines intersect, we have two pairs of opposite angles. They are called vertically opposite angles. They are equal in measure.

A transversal is a line that intersects two or more lines at distinct points.

When a transversal cuts two parallel lines, we have the following interesting relationships:

1. i) Each pair of corresponding angles are equal.
2. ii) Each pair of alternate interior angles are equal.

3. iii) Each pair of interior angles on the same side of transversal are supplementary.

class 7 maths lines and angles exercise 5.1-converted