求值：sin(π/4)cos(19π/6)tan(21π/4)急!

求值：sin(π/4)cos(19π/6)tan(21π/4)急! sin(π+π/6)-cos(π+π/4)cos(-π/2)+1求值 求值:sin(26π/3)+cos(-17π/4)= 求值：sin(π/12)+cos(π/12) sin(-π/4)求值 求值：sin(-3分之19π）+cos(-6分之25π）=? 求值:sin(-31π/6)-cos(-10π/3)-sin11π/4 求值:2sinπ/6+sin3π/2-2cosπ+2sinπ/3 sin^a+cos^(π/6+a)+1/2sin(2a+π/6)求值 求值sin²x+cos²(π/6+x)+1/2sin(2x+π/6) cos^6(π/8)-sin^6(π/8)=求值,[cos^2(π/8)-sin^2(π/8)][cos^4(π/8)+sin^4(π/8)+cos^2(π/8)sin^2(π/8)]=cos(π/4)[1-cos^2(π/8)sin^2(π/8)]=cos(π/4)[1-[sin^2(π/4)]/4]==7√2/16 求值sin25π/6+cos25π/3+tan(-25π/4)+sin(-7π/3)×cos(-13π/6)-sin(-5π/6)×cos(-5π/3) 化简求值:sin(π/4-3x)*cos(π/3-3x)-cos(π/6+3x)*sin(π/4+3x) 求值:sin的平方α+cosαcos(π/3+α)-sin的平方(π/6-α) 求值:2cosπ/2-tanπ/4+3/4tan²π/6-sinπ/6+cos²π/6+sin3π/2 -1/4cosπ 求值sin^4(π/8)+cos^4(π/8) 答对有分`求值sin^4(π/8)+cos^4(π/8)```过程 sin²(π/8)-cos²(π/8)求值 求值sinπ/8乘cosπ/8过程