InterviewSolution
Saved Bookmarks
| 1. |
Let the function `f(x) = tan^(1-) (sin x + cos x)` be defined on `[ 0, 2 pi] Then f(x) isA. increasing on `[0,pi//4) cup [ 5 pi/4, 2 pi]`B. decreasing on `(Pi//4,2pi)`C. increasing on `(0,pi//4,) cup (3 pi//4,2pi)`D. decreasing on `[pi//4,7 pi//4]` |
|
Answer» Correct Answer - A We have `f(x) = tan^(-1)""(sin x + cos x )` `rArr f(x)=(1)/(1+(sin x+cos x )^2)xx (cos x - sin x)` Now `f(x) gt 0 rArr cos x -sin x gt 0 tArr x in [0,pi//4) cup (5pi //4 ,4,2pi]` and `f(x) lt 0 rArr cos x sin x lt 0 rArr x in (pi//4,5 pi//4)` decreasing `(pi//4,5 pi//4)` |
|