Question
Question: Domain of \(f ( x ) = \sqrt { \cos ( \sin x ) } + \sqrt { \log _ { x } \{ x \} }\) ; where {.}denot...
Domain of f(x)=cos(sinx)+logx{x} ; where {.}denotes the fractional part, is
A
[1, π)
B
(0, 2π) ~ [1, π)
C
(0,2π)∼{1}
D
(0, 1)
Answer
(0, 1)
Explanation
Solution
We must have cos(sinx) > 0
⇒ π/2 > sin x ≥ −π/2, which is true for all real x. secondly logx{x} > 0.
If 0 < x < 1 ⇒ 0 < {x} < 1 ⇒ 0 < x < 1
If x > 1 ⇒ {x} ≥ 1, which is not possible. Thus domain is
(0, 1).