Hyperbola 2 Question 3

3. If the eccentricity of the standard hyperbola passing through the point (4,6) is 2 , then the equation of the tangent to the hyperbola at (4,6) is (2019 Main, 8 April II)

(a) 3x2y=0

(b) x2y+8=0

(c) 2xy2=0

(d) 2x3y+10=0

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Answer:

Correct Answer: 3. (c)

Solution:

  1. Let the equation of standard hyperbola is

x2a2y2b2=1

Now, eccentricity of hyperbola is

1+b2a2=2

a2+b2=4a2

b2=3a2

Since, hyperbola (i) passes through the point (4,6)

16a236b2=1

On solving Eqs. (ii) and (iii), we get

a2=4 and b2=12

Now, equation of tangent to hyperbola (i) at point (4,6), is

4xa26yb2=14x46y12=1xy2=12xy2=0 [from Eq. (iv)] 



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