Let P≡−1,0,Q≡0,0, and R≡3,33 be three points. Then the equation of the bisector of ∠PQR is

The slope of QR is 33−0/3−0=3i,e. θ=600Clearly, ∠PQR=1200AQ, is the angle bisector of the angle. So, line AQ, makes 1200 with the positive direction of the x-axis. Therefore, the equation of the bisector of ∠PQR is y=xtan1200or y=3x, i,e.,3x+y=0.