a semicircle has a radius of 11 . what is the approximate perimeter of the semicircle ?
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 .
add(divide(circumface(11), const_2), multiply(const_2, 11))