(sinπ/12)-(sin5π/12)+(2sinπ/8)(sin3π/8)
sinπ /14*sin3π /14*sin5π /14
(sin5π12−sinπ12)(sin5π12+sinπ12)
(sin5π/12+cos5π/12)(sinπ/12-cosπ/12)
(sin5π/12-sinπ/12)(cos5π/12+cosπ/12)=?
sinπ18sin5π18sin(-65π18)=( )
计算 sin5π/8*cos(7/8)π+sinπ/8-cos(3/8)π
确定cos7/12π,sin(-465°),tan11/3π,sin3*cos4*tan5的符号
化简 (1)、sin(α+180度)cos(-α)sin(-α-180度) (2)、sin3(-α)cos(2π+α)t
数学极限的运算lim α→π/2 (sinα-sin5α)/(cosα+cos5α)
cosπ/3+tanπ/4+3tan²π/6+sinπ/2+cosπ+sin3π/2等于?.
已知tana=2,计算①2cos(π/2+a)-cos(π-a))/sin(π/2-a)-3sin(π+a) ②sin3
若sin(π-a)=1/2+cosa,则sin3次方(π+a)+cos3次方(2π-a)=