NTA Abhyas JEE Main2020MathematicsHyperbolaPractice
Let the variable line y = k x + h is tangent to the hyperbola x 2 4 - y 2 9 = 1 . If the locus of P h , k is a conic, then which of the following statement is false about this conic?
Options
- AVertices of conic lies on y-axis
- BThe eccentricity of conic is greater than the eccentricity of given hyperbola.
- CThe centre of conic is at the origin
- DThe conic is an ellipse
Correct answer
D. The conic is an ellipse
Step-by-step solution
Equation of the tangent y = k x + h is compared with y = m x ± 4 m 2 - 9 ⇒ 1 = m k = ± 4 m 2 - 9 h i.e. m = k and h = 4 m 2 - 9 ⇒ h = 4 k 2 - 9 ⇒ 4 y 2 - x 2 = 9 ⇒ y 2 3 2 2 - x 2 3 2 = 1 ⇒ 3 2 = 3 2 2 e 2 - 1 ⇒ e 2 = 5 ⇒ e = 5 > 1 Hence, the conic is not an ellipse