On the GED Test, you will be expected to know the names and sizes of different kinds of angles.
You may already know that a right angle measures 90° and is identified by a small square.
Take the time to memorize the other angles you don't already know.
Click on their name below to see what they look like.
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Key Terms
- A right angle is an angle that makes a "squared corner," and it measures exactly 90°.
- An acute angle measures less than 90°.
- An obtuse angle measures more than 90° but less than 180°.
- A straight angle measures exactly 180°.
- A reflex angle measures more than 180° but less than 360°.
- A full circle measures 360°.
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Pay attention to the curved line that indicates openness.
It shows exactly where the angle is. If the curved line is on the "outside,"
the angle is more than 180°. It is known as a reflex angle.
Some people think that a straight angle looks like a straight line, but it is really an angle that is halfway open.
It is more like a half circle than a line. Have you ever heard the expression, "He did a one eighty?" It refers to changing direction.
Think of someone traveling west to east, who changes direction, and returns east to west.
You could also imagine a person who is sick and getting sicker, and then he or she suddenly starts to get well.
Each person in these examples does "a one-eighty" (180 °).
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