1:cos(x-π/4)=√2/2*(cosx+sinx)=√2/10
cosx+sinx=1/5
所以:sinx=4/5
2:cosx=-3/5
sin(2x+π/3)=1/2*sin2x+√3/2*cos2x
=1/2*2*sinx*cosx+√3/2*(1-2sinx*sinx)
=-12/25+9√3/50
1:cos(x-π/4)=√2/2*(cosx+sinx)=√2/10
cosx+sinx=1/5
所以:sinx=4/5
2:cosx=-3/5
sin(2x+π/3)=1/2*sin2x+√3/2*cos2x
=1/2*2*sinx*cosx+√3/2*(1-2sinx*sinx)
=-12/25+9√3/50