__CHAPTER 5 LINES AND ANGLES__ANGLE

An angle is formed when two lines meet.

Complementary angles: Two angles which add up to 900 are called complementary angles.

Supplementary angles: Two angles which add up to 180o are called supplementary angles.

Adjacent angles: Angles which have a common vertex and a common arm but no common interior.

Linear pair: Angles which are adjacent and supplementary

INTERSECTION

When two lines meet, they are said to intersect with each other. The point at which they meet is called the intersection point.

PARALLEL LINES

When two or more lines do not intersect, no matter how far they are extended, they are said to be parallel lines.

VERTICALLY OPPOSITE ANGLES

When two lines intersect like an X, the pair of opposite angles are called vertically opposite angles. Vertically opposite angles are equal.

TRANSVERSAL LINE

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

When a transversal cuts two parallel lines, there are some properties like:

- Each pair of corresponding angles is equal.
- Each pair of alternate angles is equal.
- Each pair of interior angles on the same side of the transversal are supplementary.