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r=1+cosθr = 1 + \cos\thetar=1+cosθ
polar_plot(1 + cos(x), (x, 0, 2*pi), aspect_ratio=1, color='red')
r=cos4θr = \cos 4\thetar=cos4θ
polar_plot(cos(4*x), (x, 0, 2*pi), aspect_ratio=1, color='red')