MATHS""20FUN

add a line from pt E to meet line BC , mark the interset pt as F , thus EF 垂直 to BC
So AE = BF , AB =EF. since the Hight and Width of tri. ABE and BEF are the same, their area are the same. Similarly, you can apply the same method to calculate the area of tri.EDC and FEC.
Then you will get BCE: ABE+BEF+FEC+CED
BCE:BEF+BEF+FEC+FEC (since the area is the same)
BCE:2BEF+2FEC
BCE:2(BEF+FEC)
BCE:2BCE(BEF+FEC=BCE from graph)
1:2

首先 : 假設 BC 的長度為 a ，而DC的長度為 b
長方體ABCD的面積 = 長乘闊 = BC X DC = ab
至於三角形BCE，有注意到若然以BC為底線‧那麼，將E點垂直畫一條線在BC上(暫稱為F吧)，那麼，EF的高度=DC的高度 = b，三角形BCE面積 = BC X EF 除 2 = ab/2
最後，Area of BCE : Area of ABCD = ab/2 : ab = 1: 2

Area of BCE : area of ABCD
= BC * AB / 2 : AB * BC
= 1/2 : 1
= 1 : 2