Some angles have special names.
A right angle has a measure of It corresponds to one-quarter of a full turn.
A straight angle, which is just a straight line, has a measure of It corresponds to one-half of a full turn.
A null angle has a measure of You can imagine "closing" the angle until the two sides of the angle overlap. In this case, we don't have any turn, so its measure is zero!
A full angle has a measure of You can imagine "opening" the angle until one of the sides goes all the way around. So, this is the angle between a ray and itself after it has made one full turn.
On a diagram, null and full angles can look the same, so it is up to us what we choose to call it.
Which of the following shows a right angle?
An angle of has the same measure as one-quarter of a full turn.
Among the given options, the only angle is the following:
Therefore, the correct answer is II.
Which of the following is the closest to a right angle?
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b
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Which of the following shows a straight angle?
A straight angle has a degree measure of This corresponds to one-half of a full turn.
Among the given options, the only straight angle is the following:
Therefore, the correct answer is III.
Which of the following shows an angle of $180^\circ?$
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Which of the following is the closest to a straight angle?
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What type of angle is shown in the figure above?
Notice that the vertex of is point not point So is not a straight angle.
As a result, the two rays and of our angle coincide. So, we can think of as:
- A null angle, assuming it doesn't turn at all.
- A full angle, assuming it makes one full turn.
So, the answer is "Null" or "Full."
What type of angle is $\angle BAC,$ shown in the figure above?
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a
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Full or Straight |
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b
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Other |
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c
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Right |
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Null or Full |
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e
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Straight |
