Tenemos la indeterminación de tipo
0/0,
tal que el límite para el numerador es
$$\lim_{x \to 0^+} \tan{\left(x \right)} = 0$$
y el límite para el denominador es
$$\lim_{x \to 0^+} \sqrt{\left(1 - \cos{\left(x \right)}\right)^{2}} = 0$$
Vamos a probar las derivadas del numerador y denominador hasta eliminar la indeterminación.
$$\lim_{x \to 0^+}\left(\frac{\tan{\left(x \right)}}{\sqrt{\left(1 - \cos{\left(x \right)}\right)^{2}}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \tan{\left(x \right)}}{\frac{d}{d x} \sqrt{\left(1 - \cos{\left(x \right)}\right)^{2}}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\left(1 - \cos{\left(x \right)}\right) \left(\tan^{2}{\left(x \right)} + 1\right)}{\sqrt{\left(1 - \cos{\left(x \right)}\right)^{2}} \sin{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \frac{\left(1 - \cos{\left(x \right)}\right) \left(\tan^{2}{\left(x \right)} + 1\right)}{\sin{\left(x \right)}}}{\frac{d}{d x} \sqrt{\left(1 - \cos{\left(x \right)}\right)^{2}}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\left(1 - \cos{\left(x \right)}\right) \left(\tan^{2}{\left(x \right)} + 1 - \frac{2 \cos{\left(x \right)} \tan^{3}{\left(x \right)}}{\sin{\left(x \right)}} - \frac{2 \cos{\left(x \right)} \tan{\left(x \right)}}{\sin{\left(x \right)}} + \frac{2 \tan^{3}{\left(x \right)}}{\sin{\left(x \right)}} + \frac{2 \tan{\left(x \right)}}{\sin{\left(x \right)}} + \frac{\cos^{2}{\left(x \right)} \tan^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}} + \frac{\cos^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}} - \frac{\cos{\left(x \right)} \tan^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}} - \frac{\cos{\left(x \right)}}{\sin^{2}{\left(x \right)}}\right)}{\sqrt{\cos^{2}{\left(x \right)} - 2 \cos{\left(x \right)} + 1} \sin{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\left(1 - \cos{\left(x \right)}\right) \left(\tan^{2}{\left(x \right)} + 1 - \frac{2 \cos{\left(x \right)} \tan^{3}{\left(x \right)}}{\sin{\left(x \right)}} - \frac{2 \cos{\left(x \right)} \tan{\left(x \right)}}{\sin{\left(x \right)}} + \frac{2 \tan^{3}{\left(x \right)}}{\sin{\left(x \right)}} + \frac{2 \tan{\left(x \right)}}{\sin{\left(x \right)}} + \frac{\cos^{2}{\left(x \right)} \tan^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}} + \frac{\cos^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}} - \frac{\cos{\left(x \right)} \tan^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}} - \frac{\cos{\left(x \right)}}{\sin^{2}{\left(x \right)}}\right)}{\sqrt{\cos^{2}{\left(x \right)} - 2 \cos{\left(x \right)} + 1} \sin{\left(x \right)}}\right)$$
=
$$\infty$$
Como puedes ver, hemos aplicado el método de l'Hopital (utilizando la derivada del numerador y denominador) 2 vez (veces)