NTA Abhyas JEE Main2020MathematicsParabolaPractice
Let A lies on 3 x - 4 y + 1 = 0, B lies on 4 x + 3 y - 7 = 0 and C is - 2 , 5 . If A B C D is a rhombus, then the locus of D is a conic whose length of the latus rectum is equal to
Options
- A1 0 units
- B15 units
- C5 units
- D20 units
Correct answer
A. 1 0 units
Step-by-step solution
Let, D h , k C - 2 , 5 lies on 4 x + 3 y - 7 = 0 ⇒ B C is perpendicular to 3 x - 4 y + 1 = 0 ⇒ D A is perpendicular to 3 x - 4 y + 1 = 0 ⇒ Because D A = D C so, the distance of D from 3 x - 4 y + 1 = 0 is equal to D C ⇒ h + 2 2 + k - 5 2 = 3 h - 4 k + 1 5 ⇒ 25 x + 2 2 + y - 5 2 = 3 x - 4 y + 1 2 Which represents parabola with focus - 2 , 5 and directrix is 3 x - 4 y + 1 = 0 ⇒ Length of the latus rectum is 2 - 6 - 20 + 1 5 = 10 units