sin(-14/3π)+cos(-20/3π)+tan(-53/6π)

因为sin(-x)=-sinx,cos(-x)=cosx,tan(-x)=-tanx,
sin(2π+x)=sinx,cos(2π+x)=cosx,tan(2π+x)=tanx,
故sin(-14π/3)+cos(-20π/3)+tan(-53π/6)
=-sin(14π/3)+cos(20π/3)-tan(53π/6)
=-sin(2π+2π/3)+cos((2π+2π/3)-tan(8π+5π/6)
=-sin(2π/3)+cos((2π/3)-tan(5π/6)
=-√3/2-1/2+√3/3
=-(3+√3)/6