Join
AC.
As we know that area of triangles on the same base and between the same parallels lines are equal
Therefore ,
ar(APC)=ar(BPC)... (1)
Now In quadrilateral
ACQD, we have
AD=CQand ,
AD∥CQ [Given]
Therefore, this quadrilateral ADQC with one pair of opposite sides is equal and parallel is parallelogram.
Therefore ADQC is a parallelogram.
⇒AP=PQ and CP=DP
[Since diagonals of a|| gm bisect each other]
In Δs APC and DPQ we have
AP=PQ [Proved above]
∠APC=∠DPQ [Vertically opp. ∠s]
and ,
PC=PD [Proved above]
Therefore by SAS criterion of congruence,
ΔAPC≅ΔDPQ
⇒ar(APC)=ar(DPQ) ... (2)
[Since congruent Δs have equal area]
Therefore ar(BPC)=ar(DPQ) [From (1)]
Hence , ar(BPC)=ar(DPQ)