Dựng góc a,biết: a)sina=0,5 b)cosa=0,6 c)t

Dựng góc a,biết:

a)sina=0,5 b)cosa=0,6

c)tana=5 c)cota=1/3

3 Câu trả lời

Đen2017
$\begin{matrix} \sin a = 0,5 \hfill \\ \Rightarrow {\sin ^2}a + {\cos ^2}a = 1 \hfill \\ = > {\cos ^2}a = 1 - 0,25 = 0,75 \hfill \\ \Rightarrow \cos a = \pm \frac{{\sqrt 3 }}{2} \hfill \\ \Rightarrow \tan a = \frac{{\sin a}}{{\cos a}} = \pm \frac{{\sqrt 3 }}{3} \hfill \\ \Rightarrow \cot a = \pm \sqrt 3 {\text{ }} \hfill \\ \end{matrix}$
0 Trả lời 10/08/22
Bờm
$\begin{matrix} {\text{b) }}\cos a = 0,6 \hfill \\ = > {\sin ^2}a + {\cos ^2}a = 1 \hfill \\ = > {\sin ^2}a = 1 - 0,36 = 0,64 \hfill \\ = > \sin a = \pm 0,8 \hfill \\ \Rightarrow \tan a = \frac{{\sin a}}{{\cos a}} = \pm \frac{4}{3} \Rightarrow \cot a = \pm \frac{3}{4} \hfill \\ \end{matrix}$
0 Trả lời 10/08/22
Captain
$\begin{matrix} c)\tan a = 5 = > \cot a = \frac{1}{{\tan a}} = \frac{1}{5} \hfill \\ = > {\cos ^2}a = \frac{1}{{1 + {{\tan }^2}a}} = \frac{1}{{26}} \hfill \\ = > \cos a = \pm \sqrt {\frac{1}{{26}}} \hfill \\ = > {\sin ^2}a = \frac{1}{{1 + {{\cot }^2}a}} = \frac{{25}}{{26}} \hfill \\ \Rightarrow \sin a = \pm \sqrt {\frac{{25}}{{26}}} \hfill \\ \end{matrix}$
0 Trả lời 10/08/22