I have just started curiously thinking about this. The trig functions cos and sin give the (x,y) coordinates of the unit circle. How would i go about using the trig functions to finding (x,y) coordinates of an arbitrary circle? What im saying is, the cos and sin only work for the circle x^2 + y^2 = 1 I would like a general method for finding the (x,y) coordinates of the circle (x-h)^2 + (y-k)^2 = r^2 I knwo this would involve simply transforming the original function of of a f(x)=sin(x) or f(x)=cos(x) to some form of f(x)= a * sin(bx+c) + d and f(x)= a * cos(bx+c) + d However, i cant reason out what the values of a,b,c,d would be to transform a trig function to give the (x,y) coordinates of any arbitrary circle. thanks.