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In the figure, $ABCD$ and $AEFD$ are two parallelograms. Prove that $ar(\triangle APE) : ar(\triangle PFA) = ar(\triangle QFD) : ar(\triangle PFD)$.
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Given:

$ABCD$ and $AEFD$ are two parallelograms. 

To do:

We have to prove that $ar(\triangle APE) : ar(\triangle PFA) = ar(\triangle QFD) : ar(\triangle PFD)$.

Solution:

In $\triangle AEP$ and $\triangle DFQ$,

$AE = DF$                 (Opposite sides of a parallelogram)

$\angle AEP = \angle DFQ$                   (Corresponding angles)

$\angle APE = \angle DQF$                  (Corresponding angles)

Therefore, by AAS axiom,

$\triangle AEP \cong \triangle DFQ$

This implies,

$PE = QF$            (CPCT)

$ar(\triangle AEP) = ar(\triangle DFQ)$.........(i)

$\triangle PFA$ and $\triangle PFD$ are on the same base $PF$ and between the same parallels

This implies,

$ar(\triangle PFA) = ar(\triangle PFD)$......…(ii)

From (i) and (ii), we get,

$\frac{\operatorname{ar}(\Delta \mathrm{AEP})}{a r(\Delta \mathrm{PFA})}=\frac{\operatorname{ar}(\Delta \mathrm{DFQ})}{\operatorname{ar}(\Delta \mathrm{PFD})}$

 Hence proved.

Updated on: 10-Oct-2022

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