Question

Cho \(sin\alpha=0,8\). Tính \(cos\alpha,tan\alpha,cot\alpha\)

Answer 1

\(cos^2\alpha=1-sin^2\alpha=1-\left(0,8\right)^2=0,36\)

\(\Rightarrow cos\alpha=0,6\)

\(1+cot^2\alpha=\dfrac{1}{sin^2\alpha}\Rightarrow cot^2\alpha=\dfrac{1}{sin^2\alpha}-1=\dfrac{9}{16}\)

\(\Rightarrow cot\alpha=0,75\)

\(tan\alpha=\dfrac{1}{cot\alpha}=\dfrac{1}{0,75}=\dfrac{4}{3}\)

Answer 2

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

Answer 3

\(sin^{2}x+cos^{2}x=1\)

\(\Leftrightarrow\)\(cos^{2}x=1-sin^{2}x\)

\(\Leftrightarrow\)\(cos^{2}x=1-(0,8)^{2}\)

\(cos^{}x=0,6\)

\(tanx=\dfrac{sinx}{cosx}=\dfrac{0,8}{0,6}=\dfrac{4}{3} \)

\(cotx=\dfrac{cosx}{sinx}=\dfrac{0,6}{0,8}=\dfrac{3}{4}\)