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Question
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 of a trapezium = `1/2 xx "sum of lengths of parallel sides" xx h`
A (☐ABCD) = `1/2 xx [l(AB) + l(DC)] xx l(AD)`
= `1/2 xx (13 + 9) xx 8`
= `1/2 xx 22 xx 8`
= 11 x 8
= 88 sq. cm
∴ The area of ☐ABCD is 88 sq. cm.
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