Compute the Limit: Question 4

I'm very rusty with trigs and I don't know where to begin with the following question. What topics should I study in trigs to be competent in Calculus? And how do I begin answering this question?

$\displaystyle \text{Compute } \lim_{x \rightarrow 0 } \sqrt{1+cos^2(x)}$

Re: Compute the Limit: Question 4

I would recommend looking up identities even though for this particular problem you will not need them (But later on they will help you simplify!). For this problem, you could just use direct substitution and receive Sqrt(2).

Re: Compute the Limit: Question 4

That's quite easy actually.

$\displaystyle \lim_{x \to 0 }\sqrt{1+\cos^2(x)}=\sqrt{1+\cos^2(0)}=\sqrt{2}$