Cho cosα = \(\frac{3}{4}\). Hãy tìm sinα, tgα, cotgα (00 < α < 900).
\(\begin{array}{l} \sin \alpha = \sqrt {1 - {{\cos }^2}\alpha } \\ = \sqrt {1 - \frac{9}{{16}}} = \frac{{\sqrt 7 }}{4} \end{array}\)
-- Mod Toán 9