In my previous class our professor let us the following limit:
$$\lim_{x\to0} \frac{\tan(x)-\sin(x)}{x-\sin(x)}$$
He solved it by applying L'Hôpital's rule as follow:
$\lim_{x\to0} \frac{\sec^2(x) - \cos(x)}{1-\cos(x)} = \lim_{x\to0} \frac{\cos^2(x) + \cos(x) + 1}{\cos^2(x)} = \frac{3}{1} = 3$
He only wrote that in the blackboard and then told us to solve it but without using L'Hôpital's rule. So I proceeded in this way:
$\lim_{x\to0} \frac{\frac{\sin(x)}{\cos(x)} - \sin(x)}{x - \sin(x)} = \lim_{x\to0} \frac{\frac{\sin(x)(1 - \cos(x))}{\cos(x)}}{x - \sin(x)} = \lim_{x\to0} \frac{\sin(x)(1 - \cos(x))}{(x - \sin(x))(\cos(x))} = \lim_{x\to0} \frac{\sin(x)(1 - \cos(x))}{(x - \sin(x))(\cos(x))}$
From there I multiply by its conjugate $(1 - \cos(x))$ but then I get more confused:
$\lim_{x\to0} \frac{\sin(x)(1 - \cos(x))}{(x - \sin(x))(\cos(x))} \frac{(1 + \cos(x))}{(1 + \cos(x))} = \lim_{x\to0} \frac{\sin^3(x)}{(x - \sin(x))(\cos(x))(1 + \cos(x))}$ ...
Can someone give me a better advice on how to get the right result.
