How to find the equation of bisector of the angle which contains a given point

First, we find out the eqns of the bisectors using angle bisector formula. One will be acute and other will be obtuse.

To find which one contains a point like origin (0,0). In the formula of angle bisector, if a1a2+b1b2 greater than 0, then the origin lies in the obtuse angle and the  + symbol gives bisector of the obtuse angle. If a1a2 + b1b2 les than  0, then 0,0 lies in the acute angle and the +ve symbol gives the bisector of the acute angle. [Ans]