Set 3: Circles (Advanced)

**Choice C is the best answer.** Arc = (angle/360) times 2 times pi times r. 4pi = (angle/360) times 8pi. angle = 180 degrees

Explanation

Answer: C

PROBLEM

A circle has radius 4 and an arc length of 4pi. What is the central angle in degrees?

178

182

180

✓ Correct

360

Detailed Explanation

Choice C is the best answer. Arc = (angle/360) times 2 times pi times r. 4pi = (angle/360) times 8pi. angle = 180 degrees

Why others are wrong:

A: 178 is incorrect because it does not satisfy the equation.

B: 182 is incorrect because it does not satisfy the equation.

D: 360 is incorrect because it does not satisfy the equation.

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