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I have a circle of radius r and access to a random number generator. What is a method to generate random (x,y) values distributed along the circle's perimeter?

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Generate a random angle $\theta$ between $0$ and $2\pi$. Take $(x,y)=(r\cos\theta, r\sin\theta)$. –  mjqxxxx Dec 7 '12 at 15:18
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up vote 4 down vote accepted

The simplest method would be to generate a random angle $\theta \in [0,2\pi]$. Then convert from polar to Cartesian with $(x,y) = (r \cos \theta , r \sin \theta)$.

Note that if your random number generator returns a number $k \in [0,1]$ then $\theta = 2\pi k$.

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