sin(A)=2/5
trig identity:
* sin^2(A)+cos^2(A)=1
* tan(A)=sin(A)/cos(A)
find: tan(A)
[tex]\begin{gathered} \sin ^2(A)+\cos ^2(A)=1 \\ (\frac{2}{5})^2+\cos ^2(A)=1 \\ \cos ^2(A)=1-\frac{4}{25} \\ \cos ^2(A)=\frac{21}{25} \\ \cos (A)=\sqrt[]{\frac{21}{25}}=\frac{\sqrt[]{21}}{5} \end{gathered}[/tex][tex]\begin{gathered} \tan (A)=\frac{\sin (A)}{\cos (A)} \\ \tan (A)=\frac{\frac{2}{5}}{\frac{\sqrt[]{21}}{5}} \\ \tan (A)=\frac{2}{\sqrt[]{21}}\approx0.436 \end{gathered}[/tex]
