Geometry and Trigonometry practice question

Answer: B. 10π

C = 2πr = 2π(5) = 10π. Choice C (25π) is the area πr² — keep the two circle formulas straight.

Why the other answers are wrong

A. 5π

5π is πr — you dropped the factor of 2 in C = 2πr, giving 10π.

C. 25π

25π is the area, πr². Circumference uses C = 2πr = 10π.

D. 50π

50π comes from squaring the radius inside the circumference formula: 2π(25). In C = 2πr the radius is not squared, so it's 2π(5) = 10π.

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