# How to get points to draw chord(diameter) on circle

I hope I am asking my Question in right forum.. I want to get set of paired points on circle using diameter. What I have is center point of circle and its diameter.

Consider black line in figure. Line is passing through center, as well as equal to diameter of circle. Red and green lines are same, only the difference is of points used/angle. Can anyone tell me a formula or solution to get random paired points on circle. I hope my Question is clear. Thanks.

• Draw the circle's circumference based on its diameter. Then, draw lines passing through the center of the circle which cuts the circle's circumference. – Yiyuan Lee Mar 20 '14 at 9:22
• @YiyuanLee can u give me hint how to draw lines passing through center of circle? – NightFury Mar 20 '14 at 9:43
• If i am not misunderstanding your question, you already have the center of the circle. Simply put a straightedge (ruler) passing through this centre and draw a line through. – Yiyuan Lee Mar 20 '14 at 9:54

 x^2 + y^2 = r^2