L：y=2x+√5 代入椭圆 9x^2+4(2x+√5)^2-36=0 即25x^2+16√5x-16=0 x1+x2= -(16√5)/25 x(中点)=1/2(x1+x2)= -(8√5)/25 代入直线方程得y(中点)=(9√5)/25距离=根号{[-(8√5)/25]^2+[(9√5)/25-√5]^2}=8/5√...