Okay .. i have a trig question for some floor plans that im trying to do.

Question

I have a right angle .

/|
/ |
c / | a
/___|
b

I have the lengths of side c and b. Both Being 28ft in length. What is the length of side a?

The way you have drawn it, or tried to draw it, c is the hypotenuse. But that means side b would have to be less than c, contrary to what you are saying.

If the sides that are both 28 feet long are the perpendicular sides, then the third side's length is
sqrt[28^2 + 28^2] = 28 sqrt 2 = 39.60 ft