An alternating current is given by
`I = i_1 cos omegat + i_2 sin omegat`.
The rms current is given by

Options

A. `(1)/(sqrt2) (I _(1) = I _(2))`
B. `(I)/(sqrt2) ( I _(1)+ I _(2)) ^(2)`
C. `(1)/(sqrt2) (I_(1) ^(2) + I _(2) ^(2)) ^( 1//2)`
D. `1/2 (I _(1) ^(2) + I _(2) ^(2)) ^( 1//2)`

Explanation

`I = I _(1) cos omega t + I _(2) sin wt `
`I = sqrt(I _(1) ^(2) + I _(2) ^(2)) sin (omega t + alpha )`
`I _(rms ) = (t _(0))/( sqrt2) = sqrt (( 1 _(1) ^(2) + 1 _(2) ^(2))/( 2))`