Given: ABCD is a parallelogram in which AQ and CP are the bisectors of ∠A and ∠C.
To prove: APCQ is a parallelogram.
Proof: In a parallelogram ABCD
∠A = ∠C
(opposite angles of a parallelogram)
\(\frac { 1 }{ 2 }\)∠A = \(\frac { 1 }{ 2 }\)∠C
∠PAQ = ∠PCQ
(as AQ bisect ∠A and PC bisect ∠C)
AB || CD
⇒ AP || CQ
APCQ is a parallelogram.
Hence proved.