Question

The length of a rectangle is five times its width.

If the area of the rectangle is 245 ft^2 , find its perimeter.

Answer 1

P = 84

Explanation:

Area = length* width or A = lw

We know that the length is 5 times its width which can also mean

`l = 5*w` or
`l=5w`

Use the formula for area and replace
`l` with
`5w` and the total area with 245

`A = lw\\245=5w(w)`

Multiply:

`245=5w^(2)`

Divide by 5

`49=w^2`

Square root of
`w^2`

`√(49)=√(w^2)`

Simplify

`7=w`

Now that we know w = 7 we can input this into the Perimeter formula

(P = 2l +2w)

P = 2(5*7)+2(7) // Note: Remember
`l` = 5*w and w = 7

P = 84

There is also a formula for this type of problem, but this explanation is for when you forget. Hope that explains things :)