2sin^2(π/8)-1,

1-2sin²π/8=sinπ/4 计算,sin(π/12)-sin(5π/12)+2sin(π/8)sin(3π/8) 2sin^2(π/8)-1, 1-2sin²*5π/8 比较大小(1)sin(-π/11)与sin(-π/17) (2)-sin(54π/7)与sin(-63π/8) (3)sin231°与cos260° cosA+cos^2A=1,sin^2A+sin^4A+sin^8A 为什么sin-sin^2=1/4 证明一个sin&cos的等式证明 1+sin^2(x)+sin^4(x)+sin^6(x)=[1-sin^8(x)]/[cos^2(x)] sinπ/2是什么意思 化简sin(α+β)+sin(α-β)+2sinαsin(3π/2-β)= 求证:sin^2/(sin-cos) - (sin+cos)/(tan^2 -1) =sin+cos (1-cos-sin)(1-sin+cos)/sin^2α-sinα sin²0+sin²1+sin²2+……+sin²180= sin²1°+sin²2°+sin²3°+.+sin²89 若sin (π/4+α)sin(π/4-α)=-1/8,则2sin²α+tanα-1/tanα-1的值为 sin(π/4+α)sin(π/4-α)=1/4 求2sin^2(a) -1+tana-1/tan 已知sin(x+π/6)=1/3,求sin(5π/6-x)+sin^2(π/3-x) 已知sin(x+π/6)=1/4,求sin(5π/6-x)+sin^2(π/3-x)