Let a, b ∈ R, b ≠ 0. Define a function f(x)= {a sin (π)/2(x-1), for x ≤ 0; (tan 2 x- sin 2 x)/(b x^3), for x>0.} If f is continuous at x=0, then 10-…

Let $\displaystyle \mathrm{a}, \mathrm{b} \in \mathbf{R}, \mathrm{b} \neq 0$. Define a function $$f(x)= \begin{cases}\mathrm{a} \sin \frac{\pi}{2}(x-1), & \text { for } x \leq 0 \\ \frac{\tan 2 x-\sin 2 x}{\mathrm{~b} x^3}, & \text { for } x>0 .\end{cases} $$ If $\displaystyle f$ is continuous at $\displaystyle x=0$, then $\displaystyle 10-\mathrm{ab}$ is equal to \_\_\_\_.