Join Date: Jul 2008
Location: Florida Panhandle
You need to draw that triangle a little more accurately. What I think you are depicting is an isosceles triangle. That is a triangle having 2 equal legs. That would be the legs going from the top to the wall.
In a triangle all angles must add to 180 degrees. In this case you have a right triangle at the top so this is a right isosceles triangle. The ratio of the legs in a right isosceles triangle is 1:1:square root of 2. You have specified that 84 is the length of the side that has the ratio of the square root of 2.
therefore your other 2 sides are 84 divided by 1.414 = 59.41 inches.