10

Set 2: Circles (Advanced)

Explanation

Answer: B

PROBLEM

Recent studies show that a circle has radius 2 and an arc length of 1pi. What is the central angle in degrees?

A circle has radius 2 and an arc length of 1pi. What is the central angle in degrees?

A.

92

B.

90

✓ Correct
C.

180

D.

88

Detailed Explanation

[Variation 1] Choice B is the best answer. Arc = (angle/360) times 2 times pi times r. 1pi = (angle/360) times 4pi. angle = 90 degrees

Why others are wrong:
A: 92 is incorrect because it does not satisfy the equation.
C: 180 is incorrect because it does not satisfy the equation.
D: 88 is incorrect because it does not satisfy the equation.

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