What are the types of Angles

Acute Angle - Measures less than 90°
Right Angle - Measures exactly 90°
Obtuse Angle - Measures greater than 90° but less than 180°
Straight Angle - Measures exactly 180°
Reflex Angle - Measures greater than 180° but less than 360°
Adjacent Angles - Angles with a common side and a common vertex. ∠1 and ∠2 are adjacent angles.
Complementary Angles - Angles whose measures add to 90°. ∠1 and ∠2 are complementary angles.
Supplementary Angles - Angles whose measures add to 180°. ∠1 and ∠2 are supplementary angles.
Vertical Angles - Angles that have a common vertex and whose sides are formed by the same lines. Vertical angles are equal in measure. ∠1 and ∠2 are vertical angles.

What is an angle?

An angle is the shape formed by two rays meeting at a common and point. An angle is represented by the symbol ∠. The angle below is written as ∠AOB.

Parts of an angle

Arms: the two rays joining to form an angle. Below, OA and OB are the arms of ∠AOB.

Vertex: the common end point at which the two rays meet to form an angle. Below, the point O is the vertex of ∠AOB.

Degrees

Degrees are the unit of measurement for angles. A circle is divided into 360 equal degrees, so that a right angle is 90°.