To Find The Center Of A Circle From Three Given Points. (Fig. 54.) Given points a, b, c, connect a, b and b, c with straight lines.

Find exact centers of these lines, and mark them d, and e, respectively; from d and e, at right angles with lines ab and bc, construct lines extending in the direction in which they will meet. The point of intersection is the center of a circle which will pass through the given points.

Fig. 52. - Construction of an Octagon.

Fig. 53. - Bisecting an Angle.

Fig. 54. - Construction of a Circle from Three Given Points.

Fig. 55. - Construction of the Greatest Possible Square WIthin a Given Circle.