Conjugate roots and De Moivre’s theorem

Conjugate roots of real polynomials

[Maximum mark: 8]Two distinct roots for the equation$z^4-12z^3+az^2+bz+325=0\text{ are }c+i\text{ and }-2+id,$where $a,b,c,d\in\mathbb R,d>0$(a) Write down the other two roots in terms of
$c$ and $d$[2](b) Find the value of $c$ and the value of $d$[6]