sin(-π/4)求值

化简求值：sin（π4−3x 求值：sin(π/12)+cos(π/12) 求值：sin[1/2arctan(-4/3)] 求值sin25π/6+cos25π/3+tan(-25π/4)+sin(-7π/3)×cos(-13π/6)-sin(- 求值：sin(π/4)cos(19π/6)tan(21π/4)急! 求值,谢谢高手! 已知 Sin（α+3/4π）= 5/13 不查表求值：cos5π/12·sinπ/12= 求值：⑴sin(-19π/3)*cos(19π/6) 化简求值:sin(π/4-3x)*cos(π/3-3x)-cos(π/6+3x)*sin(π/4+3x) 求值并比较sin(-54π/7)与sin(-63π/8)的大小 sin^a+cos^(π/6+a)+1/2sin(2a+π/6)求值 已知tanα=2,求值√2sin（α+π/4）/1+sinα-2cos^2α/2