Q1 of 77 Page 15

In Fig. 15.74, compute the aresa of quadrilateral ABCD.

Given that,

DC = 17 cm


AD = 9 cm


And,


BC = 8 cm


In Δ BCD, we have


CD2 = BD2 + BC2


(17)2 = BD2 + (8)2


BD2 = 289 – 64


=15


In Δ ABD, we have


BD2 = AB2 + AD2


(15)2 = AB2 + (9)2


AB2 = 225 – 81


= 144


=12


Therefore,


Area of Quadrilateral ABCD = Area (Δ ABD) + Area (Δ BCD)


Area of quadrilateral ABCD = (12 × 9) + (8 × 17)


= 54 + 68


= 112 cm2


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