I know that $\displaystyle -1\le \sin x\le 1$.
I also know that it is okay to write $\displaystyle -2<\sin x<2$.
But is it okay to write $\displaystyle -2\le \sin x\le 2$, although the equalities are never attained?
I know that $\displaystyle -1\le \sin x\le 1$.
I also know that it is okay to write $\displaystyle -2<\sin x<2$.
But is it okay to write $\displaystyle -2\le \sin x\le 2$, although the equalities are never attained?
It is typically bad form to include Domain just for fun, but it sometimes serves a purpose.
$\displaystyle 0 \le 1$
It is a matter of validity, not a matter of "okay". Is it valid? Feel free to write it any way you like if it serves some purpose.