A. Align b through a and draw a ray towards c, align a through b and draw a ray towards c, finally align c through the point of intersection of the previously drawn rays B. Align c through a and draw a ray towards b, align a through c and draw a ray towards b, finally align b through the point of intersection of the previously drawn rays C. Align c through b and draw a ray towards a, align b through c and draw a ray towards a, finally align a, through the point of intersection of the previously, drawn rays D. In the first two steps any two of the points may be used and a ray drawn towards the third point, which is sighted through the point of intersection of previously drawn rays in the final step.