[tex]a)\;\tan(60^{\circ})=\dfrac{90}{x}\\\\
\sqrt{3}=\dfrac{90}{x}\\\\
x=\dfrac{90}{\sqrt{3}}\\\\
x=\dfrac{90}{\sqrt{3}}\times\dfrac{\sqrt{3}}{\sqrt{3}}\\\\
x=\dfrac{90\sqrt{3}}{3}\\\\
x=30\sqrt{3}[/tex]
[tex]b)\;\sin(30^{\circ})=\dfrac{x}{100}\\\\
\dfrac{1}{2}=\dfrac{x}{100}\\\\
x=50[/tex]
