Limits to the Limit -3!

Calculus Level 3

$\large \lim_{x\to 0} \left( \frac{1 - \left[\cos(x) \sqrt{\cos(2x)} \right]}{\tan^2 x} \right)$

If the limit above can be expressed as $$\frac AB$$ where $$A,B$$ are coprime positive integers, find $$A+B$$.

×