Table of Contents

**Types of Angles**

#### There are many different types of angles. We will define them in this lesson. Study the images carefully so you understand them.

**Acute angle:**

#### An angle whose measure is less than 90 degrees. The following is an acute angle.

**Right angle:**

#### An angle whose measure is 90 degrees. The following is a right angle.

**Obtuse angle:**

#### An angle whose measure is bigger than 90 degrees but less than 180 degrees. Thus, it is between 90 degrees and 180 degrees. The following is an obtuse angle.

**Straight angle**

#### An angle whose measure is 180 degrees.Thus, a straight angle look like a straight line. The following is a straight angle.

**Reflex angle:**

#### An angle whose measure is bigger than 180 degrees but less than 360 degrees.The following is a reflex angle.

**Adjacent angles:**

#### Angle with a common vertex and one common side. <1 and <2, are adjacent angles.

**Complementary angles:**

#### Two angles whose measures add to 90 degrees. Angle 1 and angle 2 are complementary angles because together they form a right angle.

#### Note that angle 1 and angle 2 do not have to be adjacent to be complementary as long as they add up to 90 degrees

**Supplementary angles:**

#### Two angles whose measures add to 180 degrees. The following are supplementary angles.

**Vertical angles:**

#### Angles that have a common vertex and whose sides are formed by the same lines. The following(angle 1 and angle 2) are vertical angles.