9000031209

Given complex numbers $z_1=2\sqrt{2}(\cos \frac{\pi }{4}+\mathrm{i}\sin \frac{\pi }{4})$ and $z_2=\sqrt{2}(\cos \frac{7\pi }{4}+\mathrm{i}\sin \frac{7\pi }{4})$, find the product $z_1{z}_2$.