Question

Find the area of the shaded region. Write your answers in terms of pi.

Answer 1

10 (cm.²)

Explanation:

1. the area of the circle with r=12 is: πr²=144π (cm²);

2. the area of the circle with r=8 is: 64 (cm²);

3. the area of the region between the radius 8 and 12 cm is: 144-64=80 (cm²);

4. the measure for the circle is 360°, then the area of the shaded region for 45° is: 45/360=A/80; ⇒ 10 (cm²).

Answer 2

Area of shaded region is
`\pi`

Explanation:

A =
`r^(2)`θ /2

Firstly, calculate the area of sector of radius 8cm.

A =8
`\pi`

Secondly, calculate the area of sector of radius 12cm.

A = 9
`\pi`

Calculate the difference = 9
`\pi`-8
`\pi` =
`\pi`