求y=3sin(x 20°) sin(x 80°)的最大值

求y=3sin(x+20°)+sin(x+80°)的最大值

热心网友

y=3sin(x+20)+sin(x+20+60) =3sin(x+20)+sin(x+20)cos60+cos(x+20)sin60 =3sin(x+20)+0.5sin(x+20)+√3/2cos(x+20) =7/2sin(x+20)+√3/2cos(x+20)最大值√(a^2+b^2)=√(49/4+3/4)=√13