tan2x=2tanx/(1-tanx^2)=4/3
tan2x=4/3=sin2x/cos2x
sin2x^2+cos2x^2=1 x属于(0,π/2) 2x属于(0,π) tan2x>0
sin2x=4/5 cos2x=3/5
sin(2x+π/3)=sin2x cosπ/3+cos2x sinπ/3=(4+3√3)/10
tan2x=2tanx/(1-tanx^2)=4/3
tan2x=4/3=sin2x/cos2x
sin2x^2+cos2x^2=1 x属于(0,π/2) 2x属于(0,π) tan2x>0
sin2x=4/5 cos2x=3/5
sin(2x+π/3)=sin2x cosπ/3+cos2x sinπ/3=(4+3√3)/10