Identify given values

The maximum value of the sinusoidal alternating current is given as $I_m = 100A$.

$I_m = 100A$

Select the average value formula

For a full sinusoidal waveform over a half-cycle, the average value is calculated using the relationship $I_{avg} = \frac{2I_m}{\pi}$.

$I_{avg} = \frac{2 I_m}{\pi}$

Substitute and solve

Substitute $I_m = 100$ and $\pi \approx 3.14159$ into the formula: $I_{avg} = \frac{2 \times 100}{3.14159} = \frac{200}{3.14159} \approx 63.66A$.

$I_{avg} \approx 63.7A$