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KCET · Maths · Functions

The range of the function \(f(x)=\sin [x],-\frac{\pi}{4} < x < \frac{\pi}{4}\), where \([x]\) denotes the greatest integer \(\leq x\), is

  1. A \(\{0\}\)
  2. B \(\{0,-1\}\)
  3. C \(\{0, \pm \sin 1\}\)
  4. D \(\{0,-\sin 1\}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\{0,-\sin 1\}\)

Step-by-step Solution

Detailed explanation

Given, \(f(x)=\sin [x],-\frac{\pi}{4} < x < \frac{\pi}{4}\)
\(\begin{array}{ll}\text { Clearly, } & \sin 0=0 \\ \text { and } \quad & {\left[\frac{\pi}{4}\right]=\left[\frac{3.14}{4}\right]=0}\end{array}\)
\(\begin{aligned}
\therefore & \forall x \in\left[0, \frac{\pi}{4}\right], \sin [x]=0 \\
& \forall x \in\left[-\frac{\pi}{4}, 0\right],[x]=-1 \\
\therefore & \sin [x]=\sin (-1)=-\sin 1
\end{aligned}\)
So, the range of \(f(x)\) is \(\{0,-\sin 1\}\).