Answer :
The line cutting the rectangle diagonally gives you two identical triangles and the dividing line is the hypotenuse.
So we apply the Pythagorean formula:
a^2+b^2 = c^2
36^2+78^2 = c^2
1296+6084 = 7380 take the square root: sqrt7380 = 85.9
Answer 85.9 feet = round to 86
So we apply the Pythagorean formula:
a^2+b^2 = c^2
36^2+78^2 = c^2
1296+6084 = 7380 take the square root: sqrt7380 = 85.9
Answer 85.9 feet = round to 86