In rectangle ABCD, corner A is folded over crease DE to point F on BC. Find BC.
+2668 We know that \(EF = 9\)
Using the Pythagorean Theorem, \(BF = \sqrt{45}\)
Let \(DF = BC = x\)
We can derive the following equation using the Pythagorean Theorem: \(x^2=225+(x-\sqrt{45})^2\)
Solving, we find that \(\color{brown}\boxed{BC = 3 \sqrt{45}}\)
