When Is the Squeeze(Sandwich) Theorem Used? I am beginning to learn Calculus 1, and I was taught about the squeeze (sandwich) theorem. It seems to me that all the problems given have $\sin$ involved. Is this true? When is the squeeze theorem applied?  
Also, what are the standard "squeeze functions"? For example, I know that $-1\leq\sin(x)\leq 1$ and this is used in a $\sin$-involved problem. Are there other such functions to apply when using the squeeze theorem? 

No it's not necessary that sine functions are involved in all Sandwich Theorem Problems.


*

*Sandwich Theorem is commonly used in computing Integrals as a limit of a sum.

*It is used in Limit Computations

*It is used in proving convergence of many series by bounding it.

*I found another interesting use with many applications in itself. The limit of the sinc function can be proved using the theorem which provides a first order approximation that is used in Physics. This function also shows up as the fourier transform of a rectangular wave.
You can read more about this specific function in the top answer (answered anonymously) to this Quora question.
Examples of functions where squeeze theorem can be applied-
Limit of the function-
$f(x)=x^2 e^{\sin\frac{1}{x}}$
As x approaches 0
The limit is not normally defined because the function oscillates infinitely many times as it approaches zero
