過橢圓x2a2+y2b2=1(a>b>0)的焦點F(c,0)的弦中最短弦長是() A. 2b2aB. 2a2bC. 2c2aD. 2c2b

過橢圓x2a2+y2b2=1(a>b>0)的焦點F(c,0)的弦中最短弦長是() A. 2b2aB. 2a2bC. 2c2aD. 2c2b

由題意,過橢圓x2a2+y2b2=1(a>b>0)的焦點F(c,0)的弦中最短弦為過焦點垂直於x軸弦當x=c時,y=±b2a∴最短弦長是2b2a故選A.