## Polar Function
To draw a curve \(r = r(\theta)\) in polar coordinates, we can first plot \(r(\theta)\) on the \(\theta r\)-plane as a normal function. Consider the function \[r(\theta) = 2\sin (3\theta).\] On the \(\theta r\)-plane, this function is a sinusoidal curve with amplitude 2 and period \(2\pi/3\). The curve is shown in the left graph with the length of the green arrow indicating the value of \(r(\theta)\).
Joseph Lo, 27 March 2013, Created with GeoGebra |