Question

biết \(\tan\alpha=\dfrac{12}{35}\)tính \(\sin\alpha\),\(\cos\alpha\),\(\cot\alpha\)

Answer 1

Xét ABC vuông tại A, có:

\(BC^2=AB^2+AC^2=12^2+35^2=1369\)

\(BC=\sqrt{1369}=37cm\)

\(\cos B=\dfrac{AB}{BC}=\dfrac{12}{37}\)

\(\cot B=\dfrac{AB}{AC}=\dfrac{12}{35}\)

\(\sin B=\dfrac{AC}{BC}=\dfrac{35}{37}\)

Answer 2

\(tan\alpha=\frac{AC}{AB}=\frac{12}{35}\)

\(cot\alpha=\frac{AB}{BC}=\frac{35}{12}\)

\(sin\alpha=\frac{AC}{BC}=\frac{12}{37}\)

\(cos\alpha=\frac{AB}{BC}=\frac{35}{37}\)

\(BC=\sqrt{12^2+35^2}=\sqrt{1369}=37\)