JEE Advanced2015MathematicsFunctionsActual
Let f x = sin ⁡ π 6 sin ⁡ π 2 sin ⁡ x , for all x ∈ R and g x = π 2 sin ⁡ x , for all x ∈ R . Let f o g x denote f g x and g o f x denote g f x . Then which of the following is (are) true?
Options
- ARange of f is - 1 2 , 1 2
- BRange of f o g is - 1 2 , 1 2
- Clim x → 0 f ( x ) g ( x ) = π 6
- DThere is an x ∈ R such that g o f x = 1
Correct answer
A. Range of f is - 1 2 , 1 2
Step-by-step solution
f x = sin π 6 sin π 2 sin x - π 2 ≤ π 2 sin x ≤ π 2 - 1 ≤ sin π 2 sin x ≤ 1 sin - π 6 ≤ sin π 6 sin π 2 sin x ≤ sin π 6 - 1 2 ≤ sin π 6 sin π 2 sin x ≤ 1 2 f g x = sin π 6 sin π 2 sin π 2 sin x - 1 ≤ sin π 2 sin x ≤ 1 - π 2 ≤ π 2 sin π 2 sin x ≤ π 2 - 1 ≤ sin π 2 sin π 2 sin x ≤ 1 - π 6 ≤ π 6 sin π 2 sin π 2 sin x ≤ π 6 - 1 2 ≤ sin π 6 sin π 2 sin π 2 sin x ≤ 1 2 lim x → 0 f x g x = lim x → 0 sin π 6 sin π 2 sin x π 2 sin x × π 6 sin π 2 sin