A particle staring from the origin (0, 0) moves in a straight line in the (x,y) plane. Its coordinates at a later time are (, 3 ). The path of the particle makes with the x-axis an angle of:
Slope of the path of the particle gives the measure of angle required.
Draw the situation as shown. OA represents the path of the particle starting from origin O (0,0). Draw a perpendicular from point A to x-axis. Let path of the particle makes an angle with the x-axis, then
or