An angle is made up of two rays with a common end point called a vertex. The two rays of the angle are also called arms of the angle.

If fig (a) OA and OB are two rays and O is Vertex.

There are different types of angles such as acute angle, right angle, obtuse angle, straight angle, and reflex angle.

Now, we discussed some more types of angles.

**Complementary angles:**

Two angles whose sum is 90 degrees are called complementary angles.

**Here are some examples of complementary angles.**

**Supplementary angles**. Two angles whose sum is 180 degrees are called supplementary angles.

Here are some examples of supplementary angles.

**Adjacent angles**. Two angles are said to be adjacent if they have a common vertex and a common arm between the remaining two uncommon arms are called adjacent angles.

**Some examples of adjacent angles are:**

In Fig (a) angle 1 and angle 2 are adjacent angles, because they have a common vertex ‘O’ and a common arm (OC) between two uncommon arms (OA & OB)

In Fig (b), (c), (d) โ 1 and โ 2 are also adjacent angles.

In Fig (d) โ 1 and โ 2 are not adjacent angles because they do not have a common vertex and in fig (e) โ 1 and โ 2 are also not adjacent angles because they do not have a common arm.

**Note:**

- Two adjacent angles can be complementary angles {See Fig (a)}
- Two adjacent angles can be supplementary angles. {See Fig (b)}
- Two obtuse angles can be adjacent angles {See Fig (c)}
- An acute angle can be adjacent to an obtuse angle. {See Fig (d)}

**Vertically Opposite Angle**. Vertically opposite angles formed when two lines (Say AB and CD) intersect each other at the point (Say O) (See Fig)

**There are two pairs of vertically opposite angles.**

In given fig. โ 1 and โ 3 are vertically opposite angles and โ 2 and โ 4 are also vertically opposite angles.

**Note**: Vertically opposite angles are always equal.

**Corresponding Angles**. A line that intersects two or more lines at distinct points is called a Transversal (**See Fig**)

Line l intersects line m and n at points P and Q respectively. Therefore line l is a transversal line.

In the given fig. eight angles are formed.

The pairs of corresponding angles are (โ 1, โ 5), (โ 2, โ 6), (โ 4, โ 8), (โ 3, โ 7)

Corresponding angles are always equal.