Understanding Angles in the Unit Circle

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Math › Understanding Angles in the Unit Circle

Questions 1 - 2

In the unit circle, what is the angle in radians that corresponds to the point (0, -1)?

$\frac{3\pi }{2}$

$\pi$

$\frac{\pi }{2}$

$2\pi$

Explanation

On the unit circle, (0,-1) is the point that falls between the third and fourth quadrant. This corresponds to $\frac{3\pi }{2}$ .

What is the reference angle for $\frac{16\pi}{3}$ ?

$\frac{4\pi}{3}$

$\frac{\pi}{3}$

$\frac{\pi}{6}$

$\frac{3\pi}{4}$

Explanation

To find the reference angle, subtract $2\pi$ (1 trip around the unit circle) from the given angle until you reach an angle which is less than $2\pi$ .

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