椭圆内接三角形本文是指以短轴为顶点的内接等腰三角形或等腰直角三角形 ,其余的显然由文[1]可再作研究 ,下面针对一道习题作一探讨。题　设椭圆 x2a2 +y2b2 =1(a b 0 )的两焦点为F1、F2 ,长轴两端点为A1,A2 ,若椭圆上存在一点Q ,使∠A1QA2 =12 0° ,求椭圆离心率e的范围解　 The intrinsic triangle of the ellipse refers to the inscribed isosceles triangle or isosceles right triangle with the short axis as the vertex. The rest are obviously studied by the text [1]. The following is a discussion of an exercise. Set the two focal points of the ellipse x2a2 +y2b2 = 1(ab 0) as F1, F2, the endpoints of the major axis as A1, A2, if there is a point Q on the ellipse, make ∠A1QA2 = 12 0°, find the eccentricity of the ellipse e Range solution