Question

Cho \(tan\alpha=\dfrac{7}{24}\)Tính \(sin\alpha,cos\alpha,cot\alpha\)

Answer 1

-Dựa vào cthuc \(tana.cotga=1\)

=>cotga=?

-dựa vào cthuc \(1+tan^2a=\dfrac{1}{cos^2a}\)

=>cosa=?

-dựa vào \(tana=\dfrac{sina}{cosa}\)

=>sina=?

Answer 2

\(cot\alpha=\dfrac{1}{tan\alpha}=\dfrac{24}{7}\)

\(1+tan^2\alpha=\dfrac{1}{cos^2\alpha}\Rightarrow cos^2\alpha=\dfrac{576}{625}\Rightarrow cos\alpha=\dfrac{24}{25}\)

\(1+cot^2\alpha=\dfrac{1}{sin^2\alpha}\Rightarrow sin^2\alpha=\dfrac{49}{625}\Rightarrow cos\alpha=\dfrac{7}{25}\)