In fig., A, B and C are points on OP, OQ and OR respectively such that AB ∥ PQ and AC∥ PR. Show that BC ∥ QR.
In △OPQ, we have
AB ∥ PQ
⇒ OAAP = OBBQ ..... (i)
△OQR, we have
BC ∥ QR
OBBQ = OCCR
From (i) and (ii), we get
OAAP = OCCR ...... (ii)
Thus, A and C are points on sides OP and OR respectively of △OPR, such that
OAAP = OCCR AC ∥PR [Using the converse of BPT]