英语几何题!If the foci of an ellipse are two points of the trisec

来源：学生作业帮编辑：神马作文网作业帮分类：英语作业时间：2024/11/18 05:00:31

英语几何题!
If the foci of an ellipse are two points of the trisection of the major axis,then the ratio of the distance between the directrix to the distance between the foci is____?

Let's assume the major axis is the x-axis,the ellipse is expressed as x²/a² + y²/b² = 1
The foci are F1(-c,0),F2(c,0),F1F2 = 2c = 2√(a² - b²)
The vertexes on the major axis are A1(-a,0),A2(a,0),A1A2 = 2a
F1 and F2 are two points of the trisection of the major axis,so A1A1 = 3F1F2
2a = 3*2√(a² - b²)
a = 3√2b/4
c = √2b/4
Its directrixes are:y = ±a²/c,the distance between them is 2a²/c = 9√2b/2
2a²/c :2√(a² - b²) = 9√2b/2 :2*√2b/4 = 9

英语几何题!If the foci of an ellipse are two points of the trisec 英语智力测试题目There are two fish in the bottle.If one of two fish Find the inflection points,if any,of the following function. there are three points setting the backcloth of this transit In the figure above,if two points S and T are to be placed o The weights (重量) of two boys are in the radio 5:4.If the wei The weights of two boys are in the ratio 5:4.If the weight o Find the area of the region bounded by the ellipse whose equ If you are short of life is short,like the blink of an eye,s the short distance between two points is an intension 学科间综合题If the sum of two numbers is 6,which of the following Which of the two pencils are yours?