Answer
$phase = 10\pi$
Work Step by Step
We know that, If C is any real number and $B> 0$, then the graphs of
$y = A\sin(Bx+C)$ and $y = A\cos (Bx+C)$ will have
$Phase = C$
so in equation $y = 0.05\sin (500\pi t + 10\pi)$
b) So here $phase = 10\pi$
