Which identity is true for all angles theta\\thetatheta?
sin2theta+cos2theta=1\\sin^2\\theta + \\cos^2\\theta = 1sin2theta+cos2theta=1
sintheta+costheta=1\\sin\\theta + \\cos\\theta = 1sintheta+costheta=1
tantheta=costheta/sintheta\\tan\\theta = \\cos\\theta / \\sin\\thetatantheta=costheta/sintheta
sin(2theta)=2sintheta\\sin(2\\theta) = 2\\sin\\thetasin(2theta)=2sintheta