求cos5π/12sinπ/12

cos5π/12=sinπ/12 不查表求值：cos5π/12·sinπ/12= 为什么cos5π/12等于sinπ/12 (sin5π/12+cos5π/12)(sinπ/12-cosπ/12) (sin5π/12-sinπ/12)(cos5π/12+cosπ/12)=? cos5/12πcosπ/12+cosπ/12sinπ/6=? sin5/12π×cos5/12π怎么算? 计算cos5分之π+cos5分之2π+cos5分之3π+cos5分之4π 求sin25π/6+cos5π/3+tan(-25π/4)+sin(-7π/3)×cos(-13π/6)-sin(-5π 已知cos（6π-α）=√3/3 求cos5/6π+α-sin²（α-π/6）的值 已知角α终边上一点坐标为(sin5π/6,cos5π/6)求sinα和cosα的值 例题9和10,我知道有解析,但就是看不懂,好像是公式吧,我想知道cos5π/12是怎么变成sin的,周期不是π/2吗,乘