If O be the origin and if the co-ordinates of any two points P_1 and P_2 be respectively (x_1,y_1) ,(x_2,y_2), prove that OP_1 * OP_2 cosP_1OP_2 = x_1x_2 + y_1y_2?
1 Answer
Nov 21, 2017
Coordinates of points
Now