We can use the Pythagorean Theorem (a^2+b^2=c^2) to find the side lengths.
15^2=12^2+x^2 225=144+x 81=x Which gives us that x=9 (you have to remember to find the square root) Perimeter is 2l+2w, so 2(12)+2(9) = 42 Perimeter = 42
As for the area, we just multiply 9 by 12 to get us 108 Area = 108
