翻译:二圆的内切线 同义词1)internal tangent of two circles,二圆的内切线2)common tangent of two circles,二圆公切线3)tangent line of ellipses,椭圆的切线4)inscribed circle of a triangle,三角形的内切圆5)circumferential,圆周的切线向的6)How to Draw the Tangents of a Rotundity,圆的切线的作法