已知椭圆:的左顶点为,右焦点为,若点在上,为的中点,,且,则的离心率为( )A. B. C. D. 答案:【答案】B【解析】由椭圆的方程及题意可得,,,由可得是直角三角形,利用,可得,结合,即可求解.由题意可得:,,,所以是直角三角形,且是直角边,因为为的中点,所以,所以,即,整理可得:,即,可得,解得,故选:B
I have read the material several times but it doesn’t make any _________ to me.
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A.
meaning
B.
importance
C.
sense
D.
significance