trigonometric limit

[txguardmonkey]

So i have this problem. i can find the answer but i need to understand how to do it. i know i should use the theorem lim x->0 cosx-1/x=0, but i really dont even know how to get started, and im getting frustrated i can do the limits and derivatives when they have numbers but i have trouble with the trig functions

\(\displaystyle \displaystyle{\lim_{\theta\, \to\, 0}}\, \dfrac{\cos^2\left(\theta\right)\, -\, 1}{\theta}\)

 

[daon2]

Hint: \(\displaystyle A^2-1 = (A-1)(A+1)\)