JEE Advanced2012MathematicsHyperbolaActual
Tangents are drawn to the hyperbola x² 9 - y² 4 =1 , parallel to the straight line 2 x-y=1 . The points of contact of the tangents on the hyperbola are
Options
- A( 9 2 2 , 1 2 )
- B(- 9 2 2 ,- 1 2 )
- C(3 3 ,-2 2 )
- D(-3 3 , 2 2 )
Correct answer
A. ( 9 2 2 , 1 2 )
Step-by-step solution
If slope of tangents to hyperbola x² a² - y² b² =1 is m , then equations of tangent to the hyperbola is y=m x a² m²-b² with the points of contact ( a² m . . a² m²-b² a² m²-b² ) Tangent to hyperbola x² 9 - y² 4 =1 is parallel to 2 x-y=1 , Slope of tangent =2 Points of contact are ( 9 2 9 4-4 , 4 9 4-4 ) i.e. ( 9 2 2 , 1 2 ) and ( -9 2 2 , -1 2 )