Been looking over past exam questions and came across this one. Its in polar coordinates: A particle P describes the curve r=be^[Zcot(a)]. Show that the velocity and acceleration vectors have angles a and 2a with OP (O is the origin). Z is actually theta, the angle the position vector makes with the x axis. Its derivative to time is w, a constant here. B and a are constants. I'm stumped!!!! I work out v as: bcot(a)we^(Zcot(a)).[e_1] + bwe^('').[e_2] Even with them worked out I am stumped as to show that^^^^ Any pointers??? Cheers guys!!!