It is known that the circumference of rectangle ABCD is 18, e and F are the points on the edges AB and BC respectively, and AE = BF = 1. If EF is perpendicular to BD, the area of this rectangle can be calculated

It is known that the circumference of rectangle ABCD is 18, e and F are the points on the edges AB and BC respectively, and AE = BF = 1. If EF is perpendicular to BD, the area of this rectangle can be calculated

Let AB = x, BC = y, perimeter = 2x + 2Y = 18, that is, x = 9-y; triangle EBF and triangle BCD are similar triangles, so be / BF = BC / CD; be = ab-ae = Y-1, BF = 1, BC = x, CD = y, so Y-1 = x / y, substituting x = 9-y can get y = 3, (- 3 discarded); so x = 9-3 = 6, rectangular area is 3 * 6 = 18