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Question -

If E, F, G and H are respectively the mid-points of the sides of aparallelogram ABCD, show that ar (EFGH) = 1/2 ar(ABCD).



Answer -

Given,

E, F, G and H are themid-points of the sides of a parallelogram ABCD respectively.

To Prove,

ar (EFGH) = ┬╜ ar(ABCD)

Construction,

H and F are joined.

Proof,

AD || BC and AD = BC(Opposite sides of a parallelogram)

тЗТ ┬╜ AD = ┬╜ BC

Also,

AH || BF and and DH ||CF

тЗТ AH = BF and DH = CF(H and F are mid points)

тИ┤, ABFH and HFCD areparallelograms.

Now,

We know that, ╬ФEFH andparallelogram ABFH, both lie on the same FH the common base and in-between thesame parallel lines AB and HF.

тИ┤ area of EFH = ┬╜ areaof ABFH тАФ (i)

And, area of GHF = ┬╜area of HFCD тАФ (ii)

Adding (i) and (ii),

area of ╬ФEFH┬а+area of ╬ФGHF = ┬╜ area of ABFH┬а+ ┬╜ area of HFCD

тЗТ area of EFGH = areaof ABFH

тИ┤ ar (EFGH) = ┬╜ar(ABCD)

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