# Reflex Angle Concave Polygon Homework

## Reflex Angles

Different Angles have different names:

A **Reflex Angle** is more than 180° but less than 360°

This is a reflex angle

All the angles below are reflex angles:

## Which Angle?

Remember to look carefully at which angle you are being asked to name.

The reflex angle is the larger angle.

It is more than 180° but less than 360°

If you choose the smaller angle you might have an Acute Angle, or an Obtuse Angle instead:

The larger angle is a

**Reflex Angle**,

but the smaller angle is an

**Acute Angle**

The larger angle is a

**Reflex Angle**,

but the smaller angle is an

**Obtuse Angle**

Types of AnglesAcute AnglesRight AnglesObtuse AnglesStraight AngleAngles Around a PointDegrees (Angle)Geometry Index

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**polygon**is a closed plane figure with three or more sides that are all straight.

Some examples of polygons are shown below.

The following figure is **not a polygon** as it is not a closed figure.

A **circle** is not a polygon as it does not have straight sides.

Polygons are named according to the number of sides. The names of the most common polygons are given below:

Concave Polygon

If a polygon has a reflex angle, then it is said to be a **concave polygon**.

An example of concave polygon is shown below.

Convex Polygon

If a polygon has no reflex angle, then it is said to be a **convex polygon**.

Examples of the convex polygons are shown below.

Regular Polygon

A **regular****polygon**'s sides are all of the same length and its angles are the same size.

For example, a square is a regular polygon.

Examples of regular polygons are shown below.

Irregular Polygon

If a polygon is not a regular polygon, then it is said to be an **irregular****polygon**.

For example, the quadrilateral shown below is an irregular polygon.

Key Terms

polygon, pentagon, hexagon, heptagon, octagon, nonagon, decagon, undecagon, dodecagon, concave polygon, reflex angle, convex polygon, regular polygon, irregular polygon

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