Question

If $\cos A=\frac{4}{5},\sin A=......$ and $\tan A=......$

• A. $\frac{3}{5},\frac{3}{4}$
• B. $\frac{4}{5},\frac{2}{5}$
• C. $\frac{4}{5},\frac{1}{5}$
• D. $\frac{2}{3},\frac{6}{5}$

Answer 1

The correct option is A $\frac{3}{5},\frac{3}{4}$

$\cos A=\frac{4}{5}$.

Thus, from Pythagoras theorem

$B{C}^2=A{C}^2-A{B}^2=5^2-4^2=9$

$\Rightarrow BC=3$

$\therefore \sin A=\frac{3}{5}$ and $\tan A=\frac{3}{4}$.