`theta_1` and `theta_2` are the inclination of lines `L_1a n dL_2` with the x-axis. If `L_1a n dL_2` pass through `P(x_1,y_1)` , then the equation of one of the angle bisector of these lines is
(a) `(x-x_1)/(cos((theta_1-theta_2)/2))=(y-y_1)/(sin((theta_1-theta_2)/2))` (b)`(x-x_1)/(-sin((theta_1-theta_2)/2))=(y-y_1)/(cos((theta_1-theta_2)/2))` (c)`(x-x_1)/(sin((theta_1-theta_2)/2))=(y-y_1)/(cos((theta_1-theta_2)/2))` (d)`(x-x_1)/(-sin((theta_1+theta_2)/2))=(y-y_1)/(cos((theta_1+theta_2)/2))`