Question

a rectangle ABCD, which measure 9 ft by 12 ft, is folded once perpendicular to diagonal AC so that the opposite vertices A and C coincide. Find the length of the fold.

Answer 1

Best way to start this would be to draw a picture:


here's a start, now we need to see what the rectangle crease should look like with A folded onto C

Answer 2

I had to do this in real life to see what it should look like: