It starts with the incircle Cr around the centre I with the radius r and then draw two to each other perpendicular chords WY and XZ in the incircle Cr. At the endpoints of the chords draw the tangents a, b, c and d to the incircle. These intersect at four points A, B, C and D, which are the vertices of a bicentric quadrilateral.[6] To draw the circumcircle, draw two perpendicular bisectors p1 and p2 on the sides of the bicentric quadrilateral a respectively b.