## Precalculus (6th Edition) Blitzer

The banking angle B is $32{}^\circ$when the turning radius is $r=3.5 feet$.
As the banking angle varies inversely as the cycle’s turning radius: $B\propto \frac{1}{r}$ Using the proportionality constant k. $B=\frac{k}{r}$ As $B=28{}^\circ$ and $r=4$ , we have \begin{align} & B=\frac{k}{r} \\ & 28=\frac{k}{4} \\ & k=28(4) \\ & k=112 \end{align} Substitute the value of k in $B=\frac{k}{r}$ $B=\frac{112}{r}$ When $r=2.5$ then,   $B=\frac{112}{2.5}={{32}^{o}}$