TeX Quellcode:
z_1\cdot z_2=r_1e^{i\varphi_1} \cdot r_2e^{i\varphi_2} = r_1r_2e^{i\varphi_1+i\varphi_2} = r_1r_2e^{i(\varphi_1+\varphi_2)}