Kinds of Angles

4.NC.MD.6

In this lesson, we will identify and draw angles.

Six Types of Angles

In this lesson students will learn how to identify different types of angles.

Right Angle

An angle of 90°, as in a corner of a square or at the intersection of two perpendicular straight lines.

Acute Angle

An acute angle is an angle that measures between 90° and 0°, meaning it is smaller than a right angle (an “L” shape) but has at least some space between the two lines that form it.

Obtuse Angle

In Geometry, an obtuse angle is an angle that is greater than 90° and less than 180°

Straight Angle

A straight angle always forms a straight line. The value of the straight angle is 180°.

Reflex Angles

A reflex angle is the larger angle, it’s always more than 180° (half a circle) but less than 360° (A full circle). It’s possibly the most confusing of the angles because it’s always on the outside.

Full Angle

A Full Angle is an angle that has a measure of exactly 360°. I looks like a circle.

Multiple Choice

What angle is shown in the picture?

• Right

• Obtuse

• Straight

• Acute

Multiple Choice

What angle is shown in the picture?

• Right

• Obtuse

• Straight

• Acute

Multiple Choice

What angle is shown in the picture?

• Right

• Obtuse

• Straight

• Acute

Multiple Choice

Ms. Sanders wants her door to open to a right angle. It is already opened 73°. How many more degrees does she need to open it to have it open at a right angle?

• Straight

• 11⁰

• 13⁰

• 17⁰

Multiple Choice

An angle whose measure is exactly 90 degrees is called what?

• Right

• Obtuse

• Full

• Acute