Page:American Journal of Mathematics Vol. 2 (1879).pdf/16

This page has been proofread, but needs to be validated.
10
Ladd, The Pascal Hexagram.

These three lines meet in a point, namely, the Brianchom point hence the two triangles formed by the vertical rows of points are homologous. The sides of the first are the Pascals and the corresponding sides of the second are hence these three pairs of sides intersect in a line which, as it is an axis of homology corresponding to the centre of homology we shall call the line In the same way it may be shown that the triangle formed by any three of the four Pascals to which the triangle belongs are homologous therewith, therefore the intersections of the four axes of homology, with the four Pascal lines respectively, are four points on one straight line. As this line is obtained by means of the triangle we shall call it the line To each triangle formed by three fundamental lines, no two of which pass through the same point on the conic, corresponds a line of the same notation; there are such triangles, hence there are lines To each point corresponds a line, hence there are lines divided into groups of four each, which intersect corresponding lines on the lines.

4. The triangles are homologous. Let us call their centre of homology their axis Let us say that the points are joined by the line and that the lines intersect in where the bar is drawn over the letters that are repeated. I have shown (Educational Times, Question 5698,) that intersect in and that are connected by There are points and lines Each point is joined to other points by lines, hence there are lines which pass by twos through the points and points which lie in twos on the lines The six lines

, ,

intersect in pairs in three points on one straight line, viz., the points on hence they form the sides of a Pascal hexagon; and for a similar reason the six points of the same notation are the vertices of a Brianchon hexagon.

5. The Brianchon hexagon formed by joining alternate vertices of has for its sides The conic inscribed