how can i write and solve(plot) a one-variable equ. that consists of several one var. expressions?

for exaple:

(a0*z1^2+c0)+(a0*z1^2-c0)*cos(2*U0+m*Pi)+b0*z1*sin(2*U0+m*Pi)=0

is an equ. that a0 & b0 & c0 & z1 & U0 are all one variable equations that determined before.