# Given radius and angle, how to find a point on a circumference.

• Apr 11th 2008, 01:41 AM
andrew2110
Given radius and angle, how to find a point on a circumference.
Hi Everyone,

I'm writing a computer game that requires me to find a set of x,y co-ordinates given the radius and angle.

Its been a few years since I was doing any kind of maths, I tried looking up on the web what would work, and came across Euclid which rang a bell, but wasnt sure if that was exactly what I needed.

Any help would be greatly appreciated.
• Apr 11th 2008, 02:43 AM
earboth
Quote:

Originally Posted by andrew2110
Hi Everyone,

I'm writing a computer game that requires me to find a set of x,y co-ordinates given the radius and angle.

...

Let C denote the center of the circle which has the coordinates $C\left(x_C, y_C\right)$

Let r denote the radius of the circle.

Then any arbitrary point P on the circle line has the coordinates:

$P\left(x_C + r \cdot \cos(\alpha)\ , \ y_C + r \cdot \sin(\alpha) \right)$
• Apr 11th 2008, 03:03 AM
andrew2110
brilliant, thanks very much for your help!