Question

A circle fits inside a semicircle of diameter 24mm

Answer 1

Answer:

The shaded are is $113\ mm^{2}$

Step-by-step explanation:

we know that

The shaded area is equal to the area of the semicircle minus the area of the circle inside the semicircle

step 1

Find the area of semicircle

The area of semicircle is equal to

$A=\frac{1}{2}\pi r^{2}$

where

$r=24/2=12\ mm$ ----> the radius is half the diameter

substitute

$A=\frac{1}{2}\pi(12)^{2}=72\pi\ mm^{2}$

step 2

Find the area of the circle inside the semicircle

The area of circle is equal to

$A=\pi r^{2}$

where

$r=12/2=6\ mm$ ---> the radius of circle inside is half the radius of semicircle

substitute

$A=\pi(6)^{2}=36\pi\ mm^{2}$

step 3

Find the shaded area

$72\pi\ mm^{2}-36\pi\ mm^{2}=36\pi\ mm^{2}$

assume

$\pi=3.14$

$36(3.14)=113.04\ mm^{2}$

3 significant figures is

$113\ mm^{2}$