The two diagonals of quadrilateral ABCD are perpendicular to each other and intersect at O. given AC = 4cm, BD = 5cm, find the area of quadrilateral ABCD
The diagonal is vertical, which means that the quadrilateral is composed of two right triangles
Take BD as the base and assume that the intersection of the diagonals is o
Then the area of BD × Ao △ 2 + BD × OC △ 2 can be changed into BD × (AO + OC) △ 2
That is BD × AC △ 2
So area = 4 × 5 △ 2
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