复数乘法 【一IP 设z1=r(cos8+isin0), z2 =r (cos2 +isin 02) z1z2 =rz (cose +isin )(cos +isin 2) =r[cos(8,+82)+isin(8,+82)]复数乘法 设 (cos sin ), 1 1 1 1 z = r +i (cos sin ) 2 2  2  2 z = r +i (cos sin )(cos sin ) 1 2 1 2 1 1 2 2 z z = rr +i +i [cos( ) sin( )] = 1 2 1 + 2 + 1 + 2 rr i