\[\boxed{\mathbf{1052}\mathbf{.}}\]
\[tg\ a = 0,5:\]
\[tg\ 2a = \frac{2\ tg\ a}{1 - tg^{2}\text{\ a}}\]
\[tg\ 2a = \frac{2 \bullet 0,5}{1 - (0,5)^{2}} = \frac{1}{1 - 0,25} =\]
\[= \frac{1}{0,75} = \frac{4}{3}\]
\[Ответ:\ \ \frac{4}{3}.\]