Question

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Which of the following could be the measure of the angle below?
–180°
–120°
140°
510°

Answer 1

The correct option is A.

Explanation:

From the given graph it is clear that the measure of angle is 180 or coterminal angles of 180 because the angle lie on a straight line.

It means the angle is in the form of

`180+360n`

Where, n can be any integer.

At n=-1.

`180+360(-1)=-180`

At n=0.

`180+360(0)=180`

At n=1.

`180+360(1)=540`

Only the angle -180° is coterminal angle of 180°. Therefore the measure of given angle is -180° and the correct option is A.

Answer 2

The measure will be 180° ± n×360° for some integer n.

For n = -1, the first choice is obtained: -180°