Question

Find the area of the shaded regions. Give your answer as a completely simplified exact value in terms of π (no approximations)

Answer 1

18π
`cm^(2)`

Explanation:

Firstly we will have to find the area of the whole circle so we do....

`A_(circle) =` π
`r^(2)`

`A_(circle) =`
`9^(2)`π

`A_(circle) =` 81π
`cm^(2)`

If we are talking about a whole circle the angels in the middle will be equal to 360°. But in our case we are only talking about 80° out of 360°. In other words we have to find out the area what
`(80)/(360)` (in other words
`(2)/(9)` )from the whole area is equal to. So we do....

81π
`cm^(2)` x
`(2)/(9)` = 18π
`cm^(2)`