（sin25π/12*cos11π/6)-(cos11π/12*sin5π6)

（sin25π/12*cos11π/6)-(cos11π/12*sin5π6)
=（sinπ/12*cosπ/6)-(-cosπ/12*sinπ/6)
=sinπ/12*cosπ/6+cosπ/12*sinπ/6
=sin(π/12+π/6)
=sin(π/4)
=√2/2
诱导公式请看下在参考资料

sin25π/12cos11π/6-cos11π/12sin5π/6
=sinπ/12cosπ/6+cosπ/12sinπ/6
=sin(π/12+π/6)
=sinπ/4