sin(2a+π/3)=2sin(a+π/6)cos(a+π/6)=2×3/5×4/5=24/25sin(2a+π/12)=sin(2a+π/3-π/4)=sin(2a+π/3)cosπ/4+cos(2a+π/3)sinπ/4=24/25×√2/2+7/25×√2/2=31√2/50