Question 606640
 X^2 + (X + 7)^2 = 13^2   (Pythagorean theorem)

X^2 + X^2 + 14X + 49 = 169

2X^2 + 14X = 120

X^2 + 7X = 60

X(X+7) = 60

     X = 5  WIDTH OF STAGE

  X+ 7 = 12 LENGTH OF STAGE