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Estimate, measure and compare angles using degrees. Construct angles using a protractor (ACMMG112)

Source: Australian Curriculum, Assessment and Reporting Authority (ACARA)

Types of angles

When we estimate and compare angles, we need to have something to compare them to. We begin with a revolution, and later we use a right angle as the angle of comparison.


We start with a full revolution. A full turn around the vertex is 360°.

A full 360 degree around a vertex
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Straight angle

A straight angle is half a revolution; the arms of the angle make a straight line. A straight angle measures 180°.

A straight line with an arrow marking the 180 degree angle in a straight line.
Straight line 180°
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