Express (cos2θ+isin2θ)−5 (cos3θ−isin3θ)6 (sinθ−icosθ)3 in the form of A+iB is
sinθ-icosθ= -i2 sinθ-icosθ = -i(cosθ+isinθ)
Given expression is
(−i)3 [cos(-10θ-18θ+3θ+isin(-25θ)]
=i(cos25θ - ising 25 θ ] .