Plot interval for inverse cos

I'm trying to plot a ratio that's periodic, so every 2pi radians, the function value should be one. The plot I'm getting shows a value much closer to zero however, so I assume I need to adjust the interval I'm plotting over, but I'm not sure how to do that or what the proper interval would be. What's the right way to approach integer values of 2pi such that my plot is accuracte and the function value is one at these places?

The plot I'm getting looks like this:

And it should look like this:

x=linspace(0,5*pi)
y3=(1-0.5)^2./(1+0.5^2-2*0.5*cos(x))
y4=(1-0.9)^2./(1+0.9^2-2*0.9*cos(x))
y6=(1-0.99)^2./(1+0.99^2-2*0.99*cos(x))

plot(x,y3,x,y4,x,y6)

Answer 1

[the cyclist]

Instead of the default value, increase the number of points used in linspace. For example,

x=linspace(0,5*pi,1000)

[Orennia Goetzinger]

Thank you!!