In triangle ABC, EF parallel BC, s triangle AEF = s triangle BCE, if s triangle ABC = 1, then s triangle CEF =? Process!

In triangle ABC, EF parallel BC, s triangle AEF = s triangle BCE, if s triangle ABC = 1, then s triangle CEF =? Process!

Let eg be parallel to AC and BC be intersected with G. let the area of triangle CEF = A and BG / GC = k, then CF / AF = kceg area = CEF area = abeg area = k × CEG area = kaaef area = CEF area / k = A / kaef area = BCE area = Berg area + EGC area can be obtained. Therefore, a / k = Ka + a (1) ABC area = A / K + Ka + 2A = 1

As shown in the figure, the rectangle ABCD is folded along EF to D & # 8321;, C & # 8321; position, if ∠ C & # 8321; Fe = 115 °, calculate the ∠ AED & # 8321; degree

In the rectangular ABCD, ∵ ad ∥ BC ∥ AEF = ∥ EFC = 115 °∥ AEF + ∥ def = 180 °