Question

ABCD是正方形,BE=EC,AB=12厘米,求阴影面积.

Answer 1

△AOD∽△EOB

∵AD/BE=2/1 ∴S△AOD/S△EOB=4/1

设△EOB的面积为s,则△AOD的面积为4s

S△AED-S△BED=4s-s=1/2×12×12-1/2×6×12=36

即s=12

S△BED=s+S阴影=1/2×6×12=36

∴S阴影=36-12=24