A particle moves in such a way that its position vector varies with time as r→ = Acosωti^+Asinωtj^. The initial velocity of the particle is

Substituting r→ = Acosωti^+Asinωtj^In  v→ = dr→dt  we  have v→ = Addtcosωti^+Addtsin ωtj^                                               =  −Aωsinωti^+Aωcosωt j^At  t = 0,  v = −Aωsin 0i^+Aωcos0j^  =   Aωj^