Let x be the length of BC. Then the length of CE is (45-x). From the condition, you have this equation 18^2 + x^2 = (45-x)^2 + 20^2, saying that the two hypotenuses have equal lengths. Simplify and find x 18^2 + x^2 = 45^2 - 90x + x^2 + 20^2 90x = 45^2 + 20^2 - 18^2 90x = 2101 x == 23.344... centimeters. ANSWER