8
Answer: DSet 1: Circles (Advanced)
Explanation
PROBLEM
A circle has radius 4 and an arc length of 2pi. What is the central angle in degrees?
A circle has radius 4 and an arc length of 2pi. What is the central angle in degrees?
A.
88
B.
180
C.
91
D.✓ Correct
90
Detailed Explanation
Choice D is the best answer. Arc = (angle/360) times 2 times pi times r. 2pi = (angle/360) times 8pi. angle = 90 degrees
Why others are wrong:
A: 88 is incorrect because it does not satisfy the equation.
B: 180 is incorrect because it does not satisfy the equation.
C: 91 is incorrect because it does not satisfy the equation.