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ઉપવલય $4x^2 + 9y^2 = 36$ પરના ક્યાં બિંદુ આગળ આંતરેલ અભિલંબ રેખા $4x -2y-5 = 0$ ને સમાંતર થાય ?
$\left( {\frac{9}{5},\frac{8}{5}} \right)$
$\left( {\frac{8}{5},-\frac{9}{5}} \right)$
$\left( {-\frac{9}{5},\frac{8}{5}} \right)$
$\left( {\frac{8}{5},\frac{9}{5}} \right)$
Solution
Given ellipse is $4{x^2} + 9{y^2} = 36$
$ \Rightarrow \frac{{{x^2}}}{9} + \frac{{{y^2}}}{4} = 1$
Normal at the point is parallel to the line
$4x + 2y – 5 = 0$
Slope of normal $=2$
slope of tangent $ = \frac{{ – 1}}{2}$
Point of contact to ellipse $\frac{{{x^2}}}{{{a^2}}} + \frac{{{y^2}}}{{{b^2}}} = 1$
and line is $\left( {\frac{{{a^2}m}}{{\sqrt {{a^2}{m^2} + {b^2}} }},\frac{b}{{\sqrt {{a^2}{m^2} + {b^2}} }}} \right)$
Now, ${a^2} = 9,{b^2} = 4$
$\therefore $ point $ = \left( {\frac{{ – 9}}{5},\frac{8}{5}} \right)$