How do I calculate a point on a circle’s circumference?

algorithm math trigonometry
Justin Ethier picture Justin Ethier · May 8, 2009 · Viewed 279.8k times · Source

How can the following function be implemented in various languages?

Calculate the (x,y) point on the circumference of a circle, given input values of:

  • Radius
  • Angle
  • Origin (optional parameter, if supported by the language)

Answer

Paul Dixon picture Paul Dixon · May 8, 2009

The parametric equation for a circle is

x = cx + r * cos(a)
y = cy + r * sin(a)

Where r is the radius, cx,cy the origin, and a the angle.

That's pretty easy to adapt into any language with basic trig functions. Note that most languages will use radians for the angle in trig functions, so rather than cycling through 0..360 degrees, you're cycling through 0..2PI radians.

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