(1)M到椭圆两焦点的距离之和为10,即2a=10,a=5
离心率为4/5,c=4,b^2=a^2-c^2=5^2-4^2=9,b=3
椭圆方程x^2/25+y^2/9=1
(2)F(c,0)为F(4,0),B(0,3),P(x,y),FT=3
圆有切线PT,满足PF^2=FT^2+PT^2
|PT|=|PB|,PF^2=FT^2+PB^2
(x-4)^2+y^2=3^2+x^2+(y-3)^2
整理得4x-3y+1=0
(1)M到椭圆两焦点的距离之和为10,即2a=10,a=5
离心率为4/5,c=4,b^2=a^2-c^2=5^2-4^2=9,b=3
椭圆方程x^2/25+y^2/9=1
(2)F(c,0)为F(4,0),B(0,3),P(x,y),FT=3
圆有切线PT,满足PF^2=FT^2+PT^2
|PT|=|PB|,PF^2=FT^2+PB^2
(x-4)^2+y^2=3^2+x^2+(y-3)^2
整理得4x-3y+1=0