In a ΔAXP and ΔCXB, ∠PAX=XCB (alternative angles AP||BC) AX=CX(given) ∠AXP=∠CXB (vertically opposite angles) Δ≃ΔCXB (ASA rule) ⇒AP=BC (By cpct) .....(1) Similarly QA=BC .....(2) From (1) and (2) we get AP=QA Now, AP||BC and AP=QA ar(ΔAPB)=ar(ΔACQ) [Triangles having equal bases and between the same parallels QP and BC].