How to convert complex numbers into cartesian form?

I need to convert this into cartesian form.

z4=real(5*exp(1i*2*pi*15*ty+0.9*pi));

[AndresVar]

z4 is a real number? so it's just (z4,0)

Answer 1

[Walter Roberson]

It is a real value. x will be that value and y will be 0.

If you let tyr be the real part of ty and tyi be the imaginary part then

5*exp(-(3*pi*(100*tyi - 3))/10)*cos(30*pi*tyr)