The r.m.s. value of a current given by i =( i_1 cos ω t+ i_2 sin ω t) is -

The r.m.s. value of a current given by $\displaystyle \mathrm{i}=\left(\mathrm{i}_{1} \cos \omega t+\mathrm{i}_{2} \sin \omega t\right)$ is -