PE of oscillator, U = \(\frac{1}{2}mw^2y^2\)
{y = displacement Maximum – energy of oscillator, E = \(\frac{1}{2}mw^2A^2\)}
U = \(\frac{1}{2}E\)
or \(\frac{1}{2}mw^2y^2\) = \(\frac{1}{2}mw^2A^2\)
or y2 = \(\frac{A^2}{2}\)
or y = \(\pm\frac{A}{\sqrt 2}\)