Question

What is the area of the blue shaded figure if A=28 cm and B=14 cm?

Use 3.14 to approximate π.

Answer 1

615.44cm^2

Explanation:

the big semicircle has a radius of 28cm

then you find the area of the big semicircle which is 1/2 x 28^2 x pi

pi=3.14

28^2=784

1/2 x 784 x 3.14=1230.88

the small semicircle has a radius of 14cm

1/2 x 14^2 x pi

1/2 x 196 x 3.14=307.72

since there are two small semicircle you need to times 307.72 by 2

307.72 x 2=615.44

now to find the area of the blue shaded you need to do

1230.88-615.44=615.44cm^2

Answer 2

153.86
`cm^(2)`

Explanation:

For the white semicircles:

B=14cm is also the diameter, we know r=1/2diameter, so r=1/2(14)=7

Awhite=1/2π
`r^(2)`

Awhite=1/2π(
`7^(2)`)

Awhite=76.93
`cm^(2)`

For the blue semicircle:

B=14cm is also the radius

Ablue=1/2π
`r^(2)`

Ablue=1/2π(
`14^(2)`)

Ablue=307.72
`cm^(2)`

Shaded area:

Ashaded=Ablue-2(Awhite)

We use this equation since there are two white semicircles.

Ashaded=307.72-2(76.93)

Ashaded=153.86
`cm^(2)`