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10-2. Parabola, Ellipse, Hyperbola
easy
The point of contact of the tangent $y = x + 2$ to the hyperbola $5{x^2} - 9{y^2} = 45$ is
A
$(9/2, 5/2)$
B
$(5/2, 9/2)$
C
$(-9/2, -5/2)$
D
None of these
Solution
(c) Hyperbola is $\frac{{{x^2}}}{9} – \frac{{{y^2}}}{5} = 1$.
Hence point of contact is $\left[ {\frac{{ – 9(1)}}{{\sqrt {9 – 5} }},\,\frac{{ – 5}}{{\sqrt {9 – 5} }}} \right] \equiv \left[ {\frac{{ – 9}}{2},\,\frac{{ – 5}}{2}} \right]$.
Trick : Since the point $\left( { – \frac{9}{2},\, – \frac{5}{2}} \right)$ satisfies both the equations.
Standard 11
Mathematics