Fig. 34. - Diagram for Finding Radius from a Segment.
Fig. 35. - Drawing a Circle Through Three Points.
Let A C, of Fig. 34, represent the chord of an arc From the center of A C square up the rise of the segment to B. Connect B with A and C. From the center of A B and B C square down the lines as shown. The point of crossing at D is the center of the circle, and D C is the radius.
Set off any three points, as A B C, Fig. 35. Connect A B and B C by straight lines. From the center of A B and B C square down to D, as shown, which will be the center of the circle. D B is therefore the radius of the circle which will strike the three points ABC.