[tex]\bf \textit{using the pythagorean theorem} \\\\ c^2=a^2+b^2\implies \sqrt{c^2-a^2}=b \qquad \begin{cases} c=\stackrel{hypotenuse}{25}\\ a=\stackrel{adjacent}{15}\\ b=opposite\\ \end{cases} \\\\\\ \sqrt{25^2-15^2}=b\implies \sqrt{400}=b\implies 20=b[/tex]
