in a parallelogram PQRS the bisectors of angle p and angle q meet at O . FIND angle poq
 

Angle PQR + Angle QPS = 180 (Co interior angles of a parallelogram)
Hence Half of PQR + Half of QPS = Half of 180
=> Angle PQO + Angle QPO = 90
In Triangle POQ,
Angle P + Angle Q + Angle O = 180 (angle sum property)
90 + Angle O = 180
Angle O = 90 
Hence, Anfle POQ = 90