are the diagonals of the parallelogram bisect the angles?(other than square and rhombus).

consider parallelogram ABCD, diagonal AC.

intriangles ABC, ADC,

AB=CD

AD=BC..opp sides of paralelogram

AC=AC common

so triangles are congruent.. SSS

angle BAC=angle DAC..CPCT

So the diagonal bisects the angle of the parallelogram.

simly you can prove of other angles.