Question

an a.c is given by i=(3sinwt+4coswt),find rms current

Answer 1

If the two currents (3sin(wt) and 4cos(wt)) are superimposed u would get 5sin(wt+Ф), where Ф is some phase lag. 

The rms is then Maximum value / $\sqrt{2}$ = $\frac{5}{ \sqrt{2} }$