Question

1. perimeter (terms of pi) ______ perimeter (number) ______ 20 ft. 13 ft. 12 ft. 10 ft.

Explanation:

Step1: Find the length of the semi - circle arc

The diameter of the semi - circle is 20 ft. The formula for the circumference of a full circle is $C = \pi d$. For a semi - circle, the arc length $l=\frac{1}{2}\pi d$. Substituting $d = 20$ ft, we get $l=\frac{1}{2}\pi\times20 = 10\pi$ ft.

Step2: Find the lengths of the non - circular sides

The non - circular sides are two 13 - ft sides and one 10 - ft side. The sum of these lengths is $13 + 13+10=36$ ft.

Step3: Calculate the perimeter in terms of $\pi$

The perimeter $P$ in terms of $\pi$ is the sum of the semi - circle arc length and the non - circular side lengths. So $P = 10\pi+36$ ft.

Step4: Calculate the perimeter as a number

Taking $\pi\approx3.14$, we substitute into the perimeter formula: $P=10\times3.14 + 36=31.4+36 = 67.4$ ft.

Answer:

Perimeter (terms of $\pi$): $10\pi + 36$ ft
Perimeter (number): $67.4$ ft