Solution Let: z1=r1(cosθ1+isinθ1),z2=r2(cosθ2+isinθ2)z_1=r_1(\cos\theta_1+i\sin\theta_1),\quad z_2=r_2(\cos\theta_2+i\sin\theta_2)z1=r1(cosθ1+isinθ1),z2=r2(cosθ2+isinθ2)