Let's take a look at the situation:
Since were looking at a right triangle, we can say that:
[tex]\sin 32=\frac{21}{x}[/tex]Solving for x :
[tex]\begin{gathered} \sin 32=\frac{21}{x} \\ \rightarrow x\sin 32=21 \\ \rightarrow x=\frac{21}{\sin 32} \\ \Rightarrow39.6 \end{gathered}[/tex]We get that the ramp is 39.6 inches long
