- Exam
- JEE Main
- Year
- 2021
- Date
- 1 September
- Shift
- Evening Shift
- Subject
- Mathematics
- Chapter
- Ellipse
JEE Main 2021 · 1 September · Evening Shift · Mathematics · Ellipse
Let θ be the acute angle between the tangents to the ellipse x ^ 2...
Options
- A
- B
- C
- D
Correct answer
C.
Step-by-step solution
Given,
On solving equations \left(1\right) \text{ and } \left(2\right)\dfrac{{x}^{2}}{9} + \dfrac{3 - {x}^{2}}{1} = 1⇒ {x}^{2} + 27 - 9{x}^{2} = 9⇒ 8{x}^{2} = 18⇒ {x}^{2} = \dfrac{9}{4}$
Since, point of intersection in the first quadrant.
Put, in equation \left(2\right)y = \dfrac{\sqrt{3}}{2}\dfrac{{x}^{2}}{9} + \dfrac{{y}^{2}}{1} = 1{x}^{2} + {y}^{2} = 3
Now, differentiate the equation \left(1\right)x{y}^{'} = \dfrac{- x}{9y}∴\dfrac{{x}^{2}}{9} + \dfrac{{y}^{2}}{1} = 1\left(\dfrac{3}{2}, \dfrac{\sqrt{3}}{2}\right){m}_{1} = - \dfrac{1}{3\sqrt{3}}\left(2\right)x{y}^{'} = \dfrac{- x}{y}∴{x}^{2} + {y}^{2} = 3\left(\dfrac{3}{2}, \dfrac{\sqrt{3}}{2}\right){m}_{2} = - \sqrt{3}\thetatan\theta = \left|\dfrac{{m}_{1} - {m}_{2}}{1 + {m}_{1}{m}_{2}}\right| = \left|\dfrac{- \dfrac{1}{3\sqrt{3}} + \sqrt{3}}{1 + \left(- \dfrac{1}{3\sqrt{3}}\right) ( - \sqrt{3} )}\right| = \left(\dfrac{2}{\sqrt{3}}\right)$