help me to solve this limit question.

\equation{ u = \dfrac{1}{x^2}},[br][br]\equation{\cos{(\dfrac{2}{\sqrt{u}})}^u = (1-2\sin^2{(\dfrac{1}{\sqrt{u}}}))^u},[br] [br]In the limit: \equation{\sin{(\dfrac{1}{\sqrt{u}})}}[br]is close to:[br]\equation{ \dfrac{1}{\sqrt{u}}}}[br][br][br]so the limit is:[br]\equation{(1-\dfrac{2}{u})^{u} = e^{-2}}[br][br]

[br]\equation{(1-\dfrac{2}{u})^{u} = e^{-2}}[br]