## edr1c Group Title find all solutions for cos z = 2, z=x+iy? 2 years ago 2 years ago

1. silvanx

2-iy = x

2. silvanx

2-x/i = y

3. silvanx

2-x/y = i

4. satellite73

you need to start with $\frac{1}{2}(e^{iz}+e^{-iz})=2$

5. satellite73

then to $e^{iz}+e^{-iz}=4$ and then $e^{2iz}+4e^{iz}+1=0$ solve the quadratic equation in $$e^{iz}$$

6. satellite73

typo i mean $e^{2iz}-4e^{iz}+1=0$

7. edr1c

ohh. ic. thx.

8. satellite73

yw

9. Aylen333

cos never be 2 in maths

10. Aylen333

-1<cosx<1