如图所示,正方形ABCD面积为20,AE=ED且EF=3FC,则三角形ABF的面积等于?

问题描述:

如图所示,正方形ABCD面积为20,AE=ED且EF=3FC,则三角形ABF的面积等于?

△ABF的面积=正方形ABCD面积-(△ECD+△AFE+△BCF﹚                    =20-﹙1/2√20×√20×1/2+1/2√20×3/4√20×1/2-√20×1/4√20×1/2)  &n...