\(cos^2\alpha=1-sin^2\alpha=1-\left(0,8\right)^2=0,36\)
\(\Rightarrow cos\alpha=0,6\)
\(1+cot^2\alpha=\dfrac{1}{sin^2\alpha}\Rightarrow cot^2\alpha=\dfrac{1}{sin^2\alpha}-1=\dfrac{9}{16}\)
\(\Rightarrow cot\alpha=0,75\)
\(tan\alpha=\dfrac{1}{cot\alpha}=\dfrac{1}{0,75}=\dfrac{4}{3}\)
HD để bạn tự lm cho dễ hiểu nhâ
-Dựa vào công thức sin^2a+cos^2a=1
=>cosa=?
-tana=sina/cosa
-cota=cosa/sina
\(sin^{2}x+cos^{2}x=1\)
\(\Leftrightarrow\)\(cos^{2}x=1-sin^{2}x\)
\(\Leftrightarrow\)\(cos^{2}x=1-(0,8)^{2}\)
\(cos^{}x=0,6\)
\(tanx=\dfrac{sinx}{cosx}=\dfrac{0,8}{0,6}=\dfrac{4}{3} \)
\(cotx=\dfrac{cosx}{sinx}=\dfrac{0,6}{0,8}=\dfrac{3}{4}\)
