JEE Main 202131 AugustEvening Shift
- Exam
- JEE Main
- Year
- 2021
- Date
- 31 August
- Shift
- Evening Shift
- Subject
- Mathematics
- Chapter
- Ellipse
JEE Main 2021 · 31 August · Evening Shift · Mathematics · Ellipse
The locus of mid-points of the line segments joining (- 3, - 5) and...
The locus of mid-points of the line segments joining and the points on the ellipse is :
Options
- A
- B
- C
- D
Correct answer
B.
Step-by-step solution
Parametric point on the given ellipse is
Let, the mid-point of line segments joining \left(- 3, - 5\right) is \left(h, k\right)\dfrac{2sin\theta - 3}{2} = h, \dfrac{3cos\theta - 5}{2} = k⇒ 2sin\theta = 2h + 3, 3cos\theta = 2k + 5⇒ sin\theta = \dfrac{2h + 3}{2}, cos\theta = \dfrac{2k + 5}{3}\sin^{2}\theta + \cos^{2}\theta = 1⇒ {\left(\dfrac{2h + 3}{2}\right)}^{2} + {\left(\dfrac{2k + 5}{3}\right)}^{2} = 1⇒ \dfrac{1}{4}\left[4{h}^{2} + 9 + 12h\right] + \dfrac{1}{9}\left[4{k}^{2} + 25 + 20k\right] = 1⇒ 36{h}^{2} + 16{k}^{2} + 108h + 80k + 145 = 0 is