sin(x-π/4 + π/2 )=-cos(x+π/4) 为什么会这样 sin的+π/2 不是会变 cos 为什么会这样啊?主要是不知道那个负号!
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2sin(x+π/4)sin(x-π/4)=?
已知sin(π/2-x)+sin(π-x)/cos(-x)+sin(2π-x)=2009,则tan(x+5π/4)等于?已知sin(π/2-x)+sin(π-x)/cos(-x)+sin(2π-x)=2009,则tan(x+5π/4)等于() A.-2009 B.-1/2009 C.1/2009 D.2009
y=sinx+cosx可化成_____?A.2sin(x-π/4);B.2sin(x+π/4); C.√2sin(x-π/4);D.√2sin(x+π/4);
求证:(sin 2x /(1-cos 2x) )·(sin x /(1+sin x))=tan (π/4-x/2).
函数f(x)=cos2x+cos(x+π/3)+sin(x+π/6)+3sin^2x的最小值A.0 B.2 C.9/4 D.3
f(x)=(1+cotx)sin^2x-2sin(x+π/4)sin(x-π/4)还有一题,
已知函数f(x)=(1+1 anx)sin^2x+m sin(x+π/4)sin(x-π/4)
已知sin(x+π/6)=1/4,求sin(5π/6-x)+sin^2(π/3-x)
sin^2(π/4 +x)
函数f(x)=2sin(x+π/4)sin(x-π/4)+sin2x的值域
求f【x】=2sin[x+π/4]sin[x-π/4]+sin2x的最大值
已知 sinα + cosα / sinα - cosα = 2 ,则 sin(α-5π) x sin(3π/2-α)等于A,3/4B,±3/10C,3/10D,-3/10
求sin^2(2x+π/3)的导数这样写为什么不对:[sin^2(2x+π/3)]'=[sin(2x+π/3)·sin(2x+π/3)]'=2[sin(2x+π/3)]'·sin(2x+π/3)=2cos(2x+π/3)·sin(2x+π/3)=sin(4x+2π/3)
f(x)=cos(2x-x/3)+2sin(x-π/4)sin(x+π/4)sin(x+π/4)化简.
化简:2sin(πx/8+π/4)+sin(-πx/8+π/4)=
sin(x+π/4)
证明2sin(π/4+x)sin(π/4-x)=cos2x
2sin(x-π/4)sin(x+π/4)=?答案是-cos2x 还是cos2x