BITSAT 2019
- Exam
- BITSAT
- Year
- 2019
- Subject
- Mathematics
- Chapter
- Ellipse
BITSAT 2019 · Mathematics · Ellipse
The locus of the foot of perpendicular drawn from the centre of the...
The locus of the foot of perpendicular drawn from the centre of the ellipse on any tangent to it is
Options
- A
- B
- C
- D
Correct answer
C.
Step-by-step solution
We have,
Centre of an ellipse is~\left(0, 0\right)( h, k )\dfrac{x2}{a2} + \dfrac{y2}{b2} = 1y = mx \pm \sqrt{a^{2}m^{2} + b^{2}}m( h, k )y = mx \pm \sqrt{6m^{2} + 2}⇒ k = mh \pm \sqrt{6m^{2} + 2}m = - \dfrac{h}{k}⇒ k = h\left(- \dfrac{h}{k}\right) \pm \sqrt{6m^{2} + 2}⇒ \sqrt{\dfrac{6h^{2}}{k2} + 2} = \dfrac{h^{2} + k^{2}}{k}⇒ 6h^{2} + 2k^{2} = \left(h^{2} + k^{2}\right)26x^{2} + 2y^{2} = \left(x^{2} + y^{2}\right)2.