Two waves are represented by the equations ${\mathrm{y}}_1=\mathrm{asin}\mathrm{\omega t}$ and ${\mathrm{y}}_2=\mathrm{acos}\mathrm{\omega t}$. The first wave

• A

  Leads the second by $\mathrm{\pi }$

• B

  Lags the second by $\mathrm{\pi }$

• C

  $\text{ Leads the second by }\frac{\mathrm{\pi }}{2}$

• D

  Lags the second by $\frac{\mathrm{\pi }}{2}$