# Angle basics review

CCSS Math: 4.MD.C.5
Review what an angle is and how an angle is measured.

### What is an angle?

An angle is two rays that share a $\blueD{\text{vertex}}$.
Intersecting lines or line segments also form angles.

## Practice: Identifying an angle

Problem 1
Which of the following figures is an angle?

## Measuring angles

Angles are measured in degrees.
The wider an angle is open, the greater its measure. If you compare these two angles, the first one is open wider.
So, the measure of this angle
is greater than the measure of this angle.

## Practice set: Which angle is greater?

Problem 2A
Which angle measure is greater?