A) if the area of the square is 81, than that will mean that the length of all the sides are 9. You find the Perimeter by adding up all of the sides. So that will mean you do 9+9+9+9 which equals 36.
B) The diagonal that I got for the square is 12.728. The formula to find the diagonal is d=a sqrt 2.
The answer is y = -8x - 20. If you were to use y = 8x - 20 then you'd get 4 = -44, which, obviously, is not true. To fix it all you need to do is add a negative sign in front of the 8. y = -8x - 20.
