Four simple harmonic vibrations.
`y_1=8cos omegat , y_2=4cos(omegat+pi/2), y_3=2 cos(omegat+pi), y_4=cos(omegat+(3pi)/2)` are superimposed on one another. The resulting amplitude and phase respectively
| A. |
`sqrt45 and tan^(-1)(1/2)` |
 |
| B. |
`sqrt45 and tan^(-1)(1/3)` |
| C. |
`sqrt75 and tan^(-1)2` |
| D. |
`sqrt75 and tan^(-1)(1/3)` |