設複數平面上的相異四點 $z_1,z_2,z_3,z_4$ 依序且依逆時針方向可連成一個正方形。下列哪一個選項為 $\dfrac{z_2-z_1}{z_3-z_1}$ 之值？
- $\sqrt{2}\cos(\dfrac{\pi}{4})+\sqrt{2}i\sin(\dfrac{\pi}{4})$
- $\sqrt{2}\cos(-\dfrac{\pi}{4})+\sqrt{2}i\sin(-\dfrac{\pi}{4})$
- $\dfrac{1}{\sqrt{2}}\cos(\dfrac{\pi}{4})+\dfrac{1}{\sqrt{2}}i\sin(\dfrac{\pi}{4})$
- $\dfrac{1}{\sqrt{2}}\cos(-\dfrac{\pi}{4})+\dfrac{1}{\sqrt{2}}i\sin(-\dfrac{\pi}{4})$
- $\cos(\dfrac{\pi}{4})+i\sin(\dfrac{\pi}{4})$