Using graphical means find an amplitude `a` of oscillations resulting from the superposition of the following oscillations of the same direction `:`
`(a)``x_(1)=3.0 cos (omegat+pi//3), x_(2)=8.0 sin (omega t+ pi//6),`
`(b)` `x_(1)=3.0 cos omegat, x_(2)=5.0 cos (omegat+pi//4), x_(3)=6.0 sin omegat.`
A. `14`
B. `7`
C. `4`
D. `2`
