Answer
0.150 m
Work Step by Step
Recall that $\epsilon_{0}=NBA\omega$
where $\epsilon_{0}$ is the maximum emf, N is the number of turns, B is the magnetic field, A is the area ,and $\omega$ is the angular speed.
Thus, we find:
$Area= \frac{\epsilon_{0}}{NB\omega}=\frac{75.0 V}{248\times0.170 T\times79.1 rad/s}$$=0.0225m^{2}$
Length of one side= $\sqrt {A}=\sqrt {0.0225m^{2}}=0.150 m$
