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In ☐ ABCD, l(AB) = 13 cm, l(DC) = 9 cm, l(AD) = 8 cm, find the area of ☐ ABCD.

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#### Solution

Draw perpendicular from c to line AB. Name the point E.

CE = AD = 8 cm

EB = AB - AE = AB - CD = 13 - 9 = 4cm

Area of rectangle AECD = l x b = 9 x 8 = 72 cm²

Area of Triangle BEC = `1/2` x b x h = `1/2` x 8 x 4 = 16 cm²

Area of ☐ ABCD = Area of AECD + Area of triangle BEC = 72 + 16 = 88 cm^{2}

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