A sequel to the first six books of the Elements of Euclid, containing an easy introduction to modern geometry, with numerous examples. By John Casey.

248 A SEQUEL TO EUCLID.
is one of the centres of perspective of ABC, and its first Brocard
triangle.
154. L intersects the circumcircle in isotomic points, with
respect to the triangle.
155. The circle described with the orthocentre as centre, and
radius equal to the diameter of the circumcircle, is coaxal with L
and the circumcircle.
156. The circle, L, the circumcircle, and the circumcircle of
the triangle A"B"C", formed by drawing through the vertices
of ABC parallels to its sides, are coaxal.
157. The centroid of ABC is one of the centres of similitude
of L and the polar circle.
158. The radical axis of the circumcircle and polar circle of
ABC is parallel to x, and the centroid of ABC divides the distance
between them in the 2: 1.