InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
If P and Q are two points whose coordinates are `(a t^2,2a t)a n d(a/(t^2),(2a)/t)`respectively and S is the point (a,0). Show that `1/(S P)+1/(s Q)`is independent of t.A. aB. 4aC. 2aD. `(2)/(a)` |
|
Answer» Correct Answer - C We have, `SP=sqrt(("at"^(2)-a^(2))+("at"-0)^(2))=(t^(2)+t)` Replacing t by `-(1)/(t)` in SP, we get `SQ=(2)/(t^(2))(1+t^(2))` `:. (1)/(SP)+(1)/(SQ)=(1)/(a(t^(2)+1))+(t^(2))/(a(t^(2)+1))` `rArr (1)/(SP)+(1)/(SQ)=(1)/(a)` `rArr (2SPSQ)/(SP+SQ)=2arArr HM` of SP and SQ in 2a |
|