Answer
a.$l=\frac{T^2 32.2}{4\pi^2}$
b. $l=7.341$ feet
Work Step by Step
$T(l)=2\pi \sqrt {\frac{l}{32.2}},$
a. $\frac{T}{2\pi}=\sqrt {\frac{l}{32.2}},$
$\frac{l}{32.2}=\frac{T^2}{4\pi ^2},$
$l=\frac{T^2 32.2}{4\pi^2}$
b. $l=\frac{9\times 32.2}{4\pi^2}=7.341$ feet
