An altering voltage is given by ; e=e1sinωt+e2cosωt . Then the root mean square value of voltage.
The given alternating voltage is,
e=e1sinωt+e2cosωt
e=e1sinωt+e2sin(ωt+π2)
Now, the root mean square value is,
e=√(e12+e22+2e1e2cosπ2)
e=√e12+e22