The complex form of the linear equation passing through two different points Z1 and Z2 in the complex plane is?

The complex form of the linear equation passing through two different points Z1 and Z2 in the complex plane is?

The complex form of the linear equation passing through two different points Z1 and Z2 in the complex plane is as follows:
z=z1+t(z2-z1), t∈R

The solution of the equation z2-i * Z with conjugate complex number = 1,

Z is just fictitious. It doesn't seem so clear. Just take Z as a + I * B, substitute it into the formula, simplify it slowly, and finally become a real number equation,
Just solve a and B

Find the solution of cosz = 3, Z is a complex number
1. Find the solution of the equation cosz = 3, Z is a complex number
2. Find the sum of R ^ ncosna (n from 0 to infinity), expressed by R, A. (R, a are real numbers.)

Let z = R (COSA + isina), I be the unit of imaginary number. Cosa + rcos2a + R ^ 2cos3a + +R ^ ncosna is 1 + Z + Z ^ 2 + +And because 1 + Z + Z ^ 2 + +z^n＝(z^n-1)/(z-1),...

Solving Z by complex equation Sinz + cosz = 0
sinz+cosz=0
kpi-pi/4 k=0,1,2,3.

sinZ+cosZ
=Root 2 (root 2 / 2 Sinz + root 2 / 2 cosz)
=Root 2 (cos45 Sinz + sin45 cosz)
=Root 2 sin (Z + 45)
=0
z=kpi-pi/4 k=0,1,2,3.