Question: Trouble plotting graph in Maple

I'm trying to plot a graph of cos(2*theta)*omega*t+2*(sin(theta))^2*sin(omega*t)=0 in Maple (For values of theta between 40 and 88 degrees roughly, with a fixed value of omega). I have substituted x=omega*t and tried to solve, but as I'm sure you can tell it is not outputting the graph I'm after, I was hoping somebody would be able to tell me where I am going wrong. Thanks.

v := 145000;
thetavn := (1/6)*Pi;
omegac := .1;
s := cos(2*thetabn)*x+2*sin(thetabn)^2*sin(x);
plots:-implicitplot(s = 0, thetabn = 43*Pi*(1/180) .. 88*Pi*(1/180), x = -200 .. 200, tickmarks = ["piticks", "decimalticks"], gridrefine = 4, size = [800, 600]);

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