Vocabulary

Vertex - is the point where two rays of an angle meet.

Right Angle - exactly 90°

Acute Angle - less than 90°

Obtuse Angle - greater than 90° but less than 180°

Straight Angle - exactly 180°

Vertical Angles - Two angles are vertical if they are opposite angles formed by the intersection of two lines.

Congruent Angles - angles are congruent if they have the same measure

Adjacent Angles - Two angles are adjacent if they share a common vertex, a common side, and do not overlap.

Reflex Angle - angles measuring greater than 180 degrees and less than 360 degrees. The measure of a reflex angle is added to an acute or obtuse angle to make a full 360-degree circle.

Concepts

Classify the given angle as acute, obtuse, right, reflex, or straight.

Rules

Determine the measure of the angle and then classify it as acute, obtuse, right, reflex, or straight.

Example

Drag and drop the angle names into the correct box naming the given angles. 

Solution

Acute Angle: Angle < 90°.

Obtuse Angle: 90° < Angle < 180°.

Right Angle: Angle = 90°.

Straight Angle: Angle = 180°.

Reflex Angle: 180° < Angle < 360°.

Pre-requisite Skills

Measure Angles (6.10.1)

Classify Angles (6.10.2)