Find the resulting amplitude and phase of the vibrations
`s=Acosomegat+(A)/(2)cos(omegat+(pi)/(2))+(A)/(4)cos(omegat+pi)+(A)/(8)cos(omegat+(3pi)/(2))`

Answer

A, B, C

Explanation

`S = A cos omegat - A/2 sin omegat - A/2 cos omegat + A/8 sin omegat`
`= A/2 cos omegat - (3A)/(8) sin omegat`
`= (5A)/(8) (4/5 cos omegat - 3/5 sinomegat) = (5A)/(8) cos(omegat + 37^(@))`
`rArr A' = (5A)/(8) , delta = 37^(@)`