Here’s the mathematical solution which can be applied in any language:
x = x0 + r * cos(theta)
y = y0 + r * sin(theta)
x0 and y0 are the coordinates of the centre, r is the radius, and theta is in radians. The angle is measured anticlockwise from the x-axis.
This is the code for C# specifically if your angle is in degrees:
double x = x0 + r * Math.Cos(theta * Math.PI / 180);
double y = y0 + r * Math.Sin(theta * Math.PI / 180);