A semicircle has a radius of 11. What is the approximate perimeter of the semicircle?
Choose the most appropriate option: A) 45 B) 51 C) 57 D) 63 E) 69

Rationale: the perimeter of a circle is 2 * pi * r . the perimeter of a semicircle is 2 * pi * r / 2 + 2 r = pi * r + 2 r the perimeter is pi * 11 + 2 * 11 which is about 57 . the answer is c .
Answer: C