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
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