Troy is building a rectangular garden that is 10 feet by 6 feet. what should be the length of the diagolas to ensure a 90 degree angle?

To find the length of the diagonals, Troy should use the Pythagorean Theorem.  The diagonal is going to be the hypotenuse of the triangle (the side directly across from the 90 degree angle).

a^2 + b^2 = c^2
6^2 + 10 ^2 = c^2
136 = c^2; find the square root of 136
c = 11.66 feet

Troy's diagonals are approximately 11.66 feet.

11/36 is .305 repeating