rectangle with area given

Question

can someone please tell me a formula for a rectangle if the area is already given and the length has to be double the height. for example the area is 45.5 and i don’t know the height but then the length is double the height.

Answer 1

The formula for the area of a rectangle is A=LW (here W is the same as height as posed in your question).

Suppose the known area is 200 square units. Also assume L = 2W (length is twice the height.

Therefore we have:

200 = LW.

But since L=2W we can substitute 2W for L giving:

200 = 2W(W)

or

2W²=200

To solve for W divide by 2 then use the square root property:

W² = 100

W= ±10. but we reject the -10 because a length cannot be negative.

L = 2(10) = 20.

Check:

A=LW = 10(20) = 200 and 20 is twice 10.