若3sinx+√3 cos x=2√3 sin(x+y),(-pie

若3sinx+√3 cos x=2√3 sin(x+y),(-pie


3sinx+√3 cos x=2√3(√3/2 sin x+1/2cosx)=2√3 sin(x+π/6)=2√3 sin(x+y)
y=π/6+2kπ,k屬於整數,又因為y屬於(-π,π)
所以y=π/6