sin^2(a-π/6)+sin^2(a+π/6)-sin^2a

sin^2(a-π/6)+sin^2(a+π/6)-sin^2a 化简:sin(-a)cos(2π+a)sin(-a-π) [sin(a-6π)cos(7π/2-a)]/[sin(3π+a)+sin(a-π）】= (1-sin^6a-cos^6a)/(sin^2a-sin^4a) sin(-2π-a)是等于sin(-a)? sin（-19π/6）=?已知[3Sin(π+a)+Cos(π-a)]/4Sin(-a)-Sin(5π/2+a)=2，求tan a 化简sin(2π+a) 化简求sin^2(a-π/3)+sin^2(a+π/3)+sin^2a 化简；sin^2 A+sin^2(A-π/3)+sin^2(A+π/3) 化简sin^2A+sin^(A-π/3)+sin(A+π/3) 若sin^2a sin^2(-a)化简 sin(arccos(2sin(a)))= sin^2a+cos^2(π/6+a)+1/2sin(2a+π/6) sin^a+cos^(π/6+a)+1/2sin(2a+π/6)求值 化简 sin^2a+cosacos(π/3+a)-sin^2(π/6-a)帮个小忙啊. 已知2sin(a/2)=cos(a/2),则sin(a+π/6)= 求证 cos（A）+ 根号3sin(A)=2sin(π/6+A)