Measuring angles

Kelly thinking whilst looking at the whiteboard with a variety of angles on it.

An angle is the space between two lines that start at the same point.

Angles are measured in degrees (°). They can measure between 0° and 360°.

Different types of angles include acute, obtuse, reflex and right angle.

You can measure angles using a protractor.

Activity: Measuring angles

Complete this interactive activity to better understand how to measure angles. Then put your knowledge to the test.

Measuring types of angles

Angles are classified according to their measurement.

Let's look at the different types.

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Right angle
A right angle looks like the corner of a square or the edge of a book. It is a perfect 90°, which is often shown by a small square drawn in between the two lines
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Acute
An acute angle is an angles that is less than 90°. This makes them smaller than a right angle.
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Obtuse
An obtuse angle is an angle that is bigger than 90° degrees, but doesn’t reach a straight line at 180°.
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Straight line
A straight line is 180˚
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Reflex
A reflex angle is an angle that is greater than 180°.

You can use a semi-circular protractor to measure an acute, right-angle and obtuse angle, but you need a circular protractor to measure a reflex angle.