express area A of square as function of perimeter P

1) The area, A, and perimeter, P, of a square are functions of its side length,S. Express the area as a functon of the Perimeter.

2) Express the area of a square as a function of the length of the diagonal.

Sorry, if it doens't belong in this section but...I just can't figure it out.

Re: Don't know if it belongs here but...

Do you know the formula for the perimeter of a square?
Do you know the formula for the area of a square?
What do you have to do to any given perimeter to find the length of one side?
What do you have to do with the length of a side of a square to get its area.
Put 'em together and write it as a formula.

A = ????

Re: Don't know if it belongs here but...

Alrighty, thanks a bunch I'll see how it goes.