Topic: Angles E2.2 – Types of Angles

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Ontario Curriculum Expectation:

6.E2.2 use a protractor to measure and construct angles up to 360°, and state the relationship between angles that are measured clockwise and those that are measured counterclockwise.

What is an Angle?

An angle is formed by two lines called arms. The arms meet at a point, called the vertex.

An angle is shown by drawing a curved line (called an arc) between the arms. The size of the angle is always written inside or next to the arc of the angle.

Measure the precise size of an angle with the unit called degrees (º). Degrees describes the amount an angle turns.

Here are different types of angles and their measurements:

1. Acute Angle

When an angle is less than 90º, it is called an acute angle.

2. Right Angle

A quarter of a circle is 90º. It is called a right angle.

3. Obtuse Angle

When an angle is more than 90º, it is called an obtuse angle.

4. Straight Angle

When an angle is exactly 180º, it is called a straight angle.

5. Reflex Angle

When an angle is between 180º and 360º it is called a reflex angle.