Question

How to do these two pls help !!!

Answer 1

a. i. Calculate the area of the complete semicircunference, and substract the area of both internal semicircunference.

Let A the area that we need to calculate, let B the area of the total semicircunference, and C the sum of the internal semicircunferences.

$A = B - C \\A = \pi (28)^2 - 2\pi (14)^2 \\A = \pi((28)^2 -2 (14)^2) \\A = 392\pi \ cm^2$

a. ii. The same idea. Let P the perimeter that we need to calculate, and let P' the perimeter of the total semicircunference, and Q the sum of the perimeters of the internal semicircunferences.

$P = P' - Q\\P = 2\pi (28) - 4\pi (14)\\P = 56\pi - 56\pi = 0$

b. i $A = 14^2 - 4(\pi (7)^2)/4\\A = 196 - 49\pi\ cm^2$

b. ii $P = 4(14) - 2\pi(7) = 56- 14\pi\ cm$