In: Math
How do the angle bisectors of the internal angles of a parallelogram form a rectangle?
let angles of parallelogram be alpha, beta, alpha, beta
2 alpha + 2 beta = 360 degrees
==> alpha + beta = 180
in triangle formed by angle bisectors,
alpha / 2 + beta / 2 + gamma = 180
==> gamma = 90 degrees
so angle bisectors form a right angle triangle
Since adjacent angles of the parallelogram are supplementary, the angle bisectors will meet each other at 90 degrees. So you have a quadrilateral with all four angles 90 deg each, so the quadrilateral is a rectangle.
Given below: