In Fig. 6.61, two chords AB and CD intersect each other at the point P. Prove that:
(i) Δ APC ~ Δ DPB
(ii) AP . PB = CP . DP
(i) In triangle APC and DPB,
∠CAP = ∠BDP (Angles on the same side of a chord are equal)
∠APC = ∠DPB (Opposite angles)
Hence,
Δ APC ~ Δ DPB (By AAA similarity)
(ii) Since, the two triangles are similar
Hence,
Or,
AP * PB = CP * DP
Hence, proved