定义椭圆或双曲线上一点和两焦点组成的三角形叫做焦点三角形;有一个角为直角的焦点三角形叫做焦点直角三角形.为了减少篇幅和方便叙述,先介绍几个一般性结论.性质P是椭圆xa22+yb22=1(ac≥b0,c是半焦距)或双曲线xa22-by22=1(a0,b0,c是半焦距)上的一点,O是原点,E,F是椭圆或 A triangle consisting of one or two focal points on an ellipse or hyperbola is called a focal triangle; a focal triangle with a right angle is called a right-angled triangle. To reduce space and facilitate narrative, first introduce several general conclusions. The property P is an ellipse xa22. +yb22=1 (ac≥b0,c is the half focal length) or hyperbolic xa22-by22=1 (a0,b0,c is the half focal length), O is the origin, E, F is the ellipse or