In the Pentagon ABCDE, if angle a = angle c = 90 degrees, ab = BC = de = AE + CD = 3, what is the area of the Pentagon?
Cut into three triangles △ Abe △ BCD and △ bed
The sum of area of two triangles AE * AB * 0.5 + 0.5 * BC * CD = 3 * 3 = 9
,ED=3,BE=(AB^2+AE^2)^1/2,BD=(BC^2+CD^2)^1/2
The area of △ bed is calculated by Helen's formula
Pentagon 18
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