px = cx + r * cos(a) py = cy + r * sin(a)Where the center of the circle with radius

`r`

is `(cx, cy)`

, and `a`

is the angle which changes as you go round the circle drawing the points / lines `(px, py)`

.The smaller the change in angle each time round your loop, the better the resolution of the circle.

So if you want a circle that is actually square, the angle has five values: 0

^{o}, 90

^{o}, 180

^{o}, 270

^{o}, and 360

^{o}(or their equivalent in radians) though the first and last will generate the same point. More pints, better looking circle - as the number of points you need obviously increases as the radius of the circle does because the length of its circumference is proportional to that radius.