The general formula for the sine function is `y = Asin(Bx-C)+D ` where
A is the amplitude of the function,
The period P is given by `(2pi)/B` , and
`C/B` is the phase shift of the graph (the shift left (if `C/B` is negative) or right (if `C/B` is positive)).
Here,` f(x) = 3sin(2x-pi)`
Phase shift=`pi/2` . Since, `C/B` value is positive the shift is to the right.