cos5π/12=sinπ/12 怎么算的?

cos5π/12=sinπ/12 怎么算的? sinπ/12cos5π/12等于 求cos5π/12sinπ/12 为什么cos5π/12等于sinπ/12 (sin5π/12-sinπ/12)(cos5π/12+cosπ/12)=? cos5/12πcosπ/12+cosπ/12sinπ/6=? sin(-4/3π）+cos5/6π= sin(-π/7)和sin（-π/5）、cos4/7 π 、cos5/8 π 怎么算?如题! cos5π等于= (sin5π/12+cos5π/12)(sinπ/12-cosπ/12) sinπ/8*cos5π/8 sin派/12*cos5派/12 sin5/12π×cos5/12π怎么算?请给出详细过程 谢谢高手了.. cos5π/12=√6-√2/4是怎么算出来的 把下列三角函数值从小到大排列起来：sin4/5π -cos5/4π sin32/5π cos5/12π求函数y=sin(π/6-x/3),x∈[-2π,4π]的单调递增空间. (sina5π/12+cos5π/12)(sin5π/12-cos5π/12) cos5╱12派等于?用公式怎么算? 求值cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11求详细过程和重要步骤的原因(1/4*sin8π/11*cos3π/11*cos5π/11)/2sinπ/11=(1/4*sin3π/11*cos3π/11*cos5π/11)/2sinπ/11这一步骤是怎么变过来的