Question

Scott wants to buy fencing to place around a semicircle rock garden. The diameter of the semicircle is 16 feet. Using 3.14 as pie, he calculates that he needs to buy about 25.12 feet of fencing. The fencing is sold by the foot, so he plans to buy 26 feet of fencing.

Explain why Scott’s reasoning is incorrect.


FIND THE CORRECT ANSWER (IMPORTANT)

Answer 1

Scott is wrong because he did not add the diameter that connects the arc

the fence is 41.12 feet. He would buy 42 feet

Explanation:

Circumference of a semicircle = πr + d

π = pi = 3.14

d = diameter = 16

r = radius = 16/2 = 8

the diameter is the straight line that passes through the centre of a circle and touches the two edges of the circle.

A radius is half of the diameter

( 3.14 x 8) + 16 = 41.12 feet