Câu hỏi 20
Đánh giá $$
\begin{aligned} &\log_{10}(\tan1^\circ)\\ &\quad+\log_{10}(\tan2^\circ)\\ &\quad+\log_{10}(\tan3^\circ)+\cdots\\ &\quad+\log_{10}(\tan88^\circ)\\ &\quad+\log_{10}(\tan89^\circ). \end{aligned}
$$
\begin{aligned} &\log_{10}(\tan1^\circ)\\ &\quad+\log_{10}(\tan2^\circ)\\ &\quad+\log_{10}(\tan3^\circ)+\cdots\\ &\quad+\log_{10}(\tan88^\circ)\\ &\quad+\log_{10}(\tan89^\circ). \end{aligned}
$$