Bài tập 3.87 trang 171 SBT Hình học 10

A.  \(2,77cm\).                         B.  \(2,8cm\).

C.  \(2,76cm\).                         D.  \(2,78cm.\).

A.  \( - {45^0} + n{360^0},n \in \mathbb{Z}\).

B.  \({45^0} + n{360^0},n \in \mathbb{Z}\)

C.  \({135^0} + n{360^0},n \in \mathbb{Z}\).

D.  \( - {135^0} + n{360^0},n \in \mathbb{Z}\).

A.  \({\left( { - 1} \right)^k}\).  B.  \( - 1\).

C.  \(1\).                                  D.  \(0\).

A.  \(\left\{ \begin{array}{l}x =  - 1 + t\\y = 2 + 2t\end{array} \right.\)

B.  \(\left\{ \begin{array}{l}x =  - 1 + 2t\\y = 2 + t\end{array} \right.\).

C.  \(\left\{ \begin{array}{l}x =  - 1 + 2t\\y = 2 - t\end{array} \right.\).

D.  \(\left\{ \begin{array}{l}x =  - 1 - 2t\\y = 2 - t\end{array} \right.\).