Comparing Angles
An angle is the space between two lines that start at the same point.
We measure angles in degrees. The degree symbol looks like this °. We show it next to a number like this 90°.
Types of angles
Angles can be between 0° and 360° (which is a full circle) and depending on the size of the angle, they are called different things:
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.
An acute angle is an angles that is less than 90°. This makes them smaller than a right angle.
A good way to remember this angle is to think that because it is small, it is “a cute” angle.
An obtuse angle is an angle that is bigger than 90° degrees, but doesn’t reach a straight line at 180°.
When you compare two angles, you have to think to yourself, is it smaller or bigger than 90°?
Example 1:
Look at this shape, known as a quadrilateral (a four-sided, two-dimensional shape).
Angle A is a right angle.
Which angles are acute angles?
Look carefully at the other angles and compare them to the right angle. Which angles are smaller?
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B and D are acute angles because they’re clearly smaller than a right angle.
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That means angle C is an obtuse angle because it is larger than angle A.
Example 2:
Are any of the angles below obtuse?
Compare each angle to a right angle again – which are bigger than 90°?
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A and D are obtuse since they’re clearly larger than a right angle.
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B and C are acute angles then.
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