...the perpendiculars from any point on OA, ОЛ, ОС, А В С . P, cos g" +P* COS 2" + P, COS 2 15. The locus of a point, the sum of the squares of the perpendiculars from which on the sides of a given polygon is constant, is a circle. 16. On any chord of a parabola as diameter a circle is described,...

...distance from a fixed point is proportional to its distance from a fixed line. 17. Show that a circle is the locus of a point the sum of the squares of whose distances from any number of fixed points is a constant. 18. If — , = j-', show that the circles...