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Question -

ABCD is a parallelogram whose diagonals intersect at O. If P is any point on BO, prove that:
(i) ar (╬Ф ADO) = ar(╬Ф CDO)
(ii) ar (╬Ф ABP) = ar (╬Ф CBP).



Answer -

Given: Here from the given figure we get
(1) ABCD is a parallelogram
(2) BD and CA are the diagonals intersecting at O.
(3) P is any point on BO
To prove:
(a) Area of ╬ФADO = Area of╬Ф CDO
(b) Area of ╬ФAPB = Area of╬Ф CBP
Proof: We know that diagonals of a parallelogram bisect each other.
┬аO is the midpoint of AC and BD.
Since medians divide the triangle into two equal areas
In ╬ФACD, DO is the median
┬аArea of ╬ФADO = Area of╬Ф CDO

Again O is the midpoint of AC.

In ╬ФAPC, OP is the median

тЗТ┬аAreaof┬а├ДAOP┬а=Area of┬а├ДCOP┬атАжтАж (1)

Similarly O is the midpoint of AC.

In ╬ФABC, OB is the median

тЗТ┬аAreaof┬а├ДAOB┬а=Area of┬а├ДCOB┬атАжтАж (2)

Subtracting (1) from (2) we get,

Area of ╬ФAOB тИТ Area of ╬ФAOP = Area of ╬ФCOB тИТ Area of ╬ФCOP

тЗТ┬аAreaof┬а├ДABP┬а=Area of┬а├ДCBP

Hence it is proved that

(a)┬а

(b)┬а

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