Find the Range of the Function
Question:
Write the range of the function
\[ f(x)=\cos[x] \]
where
\[
-\frac{\pi}{4}
Solution:
Since
\[
-\frac{\pi}{4}
we get
\[
-1\le[x]\le1
\]
Therefore,
\[
[x]=-1,\ 0,\ 1
\]
Hence,
\[
f(x)=\cos(-1),\ \cos0,\ \cos1
\]
\[
=\cos1,\ 1,\ \cos1
\]
Therefore, range is
\[
\boxed{\{\cos1,\ 1\}}
\]