Two waves are represented by ${y}_{1}=a\mathrm{sin}\left(\omega \text{\hspace{0.17em}}t+\frac{\pi }{6}\right)$ and ${y}_{2}=a\mathrm{cos}\omega \text{\hspace{0.17em}}t$. What will be their resultant amplitude

(1) a

(2) $\sqrt{2}\text{\hspace{0.17em}}a$

(3) $\sqrt{3}\text{\hspace{0.17em}}a$

(4) 2a