@factory+cos

蒲萱纨2963x=cos(sin@+cos@) y=sin(sin@+cos@) -
骆连缸19342245069 ______ x2+y2=1+2sin@cos@,sin@cos@=(x2+y2-1)/2 x*y=sin@cos@(1+2sin@cos@) 曲线方程:(x2+y2)*(x2+y2-1)-2xy=0

蒲萱纨2963cos@+cos2@+cos3@+.+cosn@化简后结果是 什么 -
骆连缸19342245069 ______[答案] cos@+cos2@+cos3@+.+cosn@ =(2sinacosa+2sinacos2a+...+2sinacosna)*1/2sina =(sin2a+(sin3a-sina)+(sin4a-sin2a)+...+(sin(n+1)a-sin(n-1)a))*1/2sina =(sin(n+1)a+sinna-sina)*1/2sina =2sin(2n+1)a/2cosa/2*1/2sina-1/2 =sin(2n+1)a/2 / 2sina/2 -1/2

蒲萱纨2963化简sinαcosα(tanα+cotα) -
骆连缸19342245069 ______[答案] sin@cos@(sin@/cos@+cos@/sin@) =sin@cos@((sin@的平方+cos@的平方)/sin@cos@) =1

蒲萱纨2963|sin@|+|cos@|在不同象限的取值范围 -
骆连缸19342245069 ______ sin@+cos@=sqr(2)*sin(@+45) 第一象限: (1,根号2] 第二象限: (-1,1) 第三象限: [-sqr(-2),-1) 第四象限: (-1,1)

蒲萱纨2963已知函数(x)=1/2(sin2xsin@+cos平方xcos@ - 1/2sin(π/2+@),(0<@<π)其图像过(π/6,1/2)
骆连缸19342245069 ______ <p>@是α..? </p> <p>f(π/6)=√3/4sinα+3/4cosα-1/2cosα</p> <p>=√3/4sinα+1/4cosα</p> <p>=1/2(√3/2sinα+1/2cosα)</p> <p>=1/2sin(α+π/6)</p> <p>=1/2</p> <p>sin(α+π/6)=1</p> <p>α+π/6=2kπ+π/2</p> <p>ψ=2kπ+π/3,k∈Z</p> <p></p>

蒲萱纨2963在三角函数中我们常用公式sin(α+β)=sinαcosβ+cosα·sinβ来进行计算 -
骆连缸19342245069 ______ sin(75°)=sin(30°+45°) =sin30°cos45°+cos30°·sin45° =0.5*(√2)/2+(√3)/2*(√2)/2 (√3)/2是二分只根号三 (√2)/2是二分只根号二 =(√6)/2+*(√2)/4

蒲萱纨29631+sin2@ - cos2@/1+sin2@+cos2@ -
骆连缸19342245069 ______ cos2@ sin2@=2sin@•cos@ 原式=[1+2sin@•cos@-(1-cos²@)]/[1+2sin@•cos@+(2cos²@-1)]=[2sin@(cos@+sin@)]/[2cos@(sin@+cos@)]=sin@/cos@=tan@

蒲萱纨2963sin &+sin@=1/2 ,cos&+cos@=1/3,求cos[& - @]的值? -
骆连缸19342245069 ______ cos(β-α)=cosαcosβ+sinαsinβ sinβ+sinα=1/2 ,cosα+cosβ=1/3, sin²β+sin²α+2sinβsinα=1/4 cos²α+cos²β+2cosαcosβ=1/9 cos(β-α)=cosαcosβ+sinαsinβ =-3/8-8/9=-59/72

蒲萱纨2963cosπ/7+cos3π/7+cos5π/7 =? -
骆连缸19342245069 ______ cosπ/7+cos3π/7+cos5π/7 =(sinπ/7cosπ/7+sinπ/7cos3π/7+sinπ/7cos5π/7)/sinπ/7 =[sin2π/7+(sin4π/7-sin2π/7)+(sin6π/7-sin4π/7)]/(2sinπ/7) 括号里用积化和差=sin6π/7/(2sinπ/7) =sin(π-π/7)/(2sinπ/7) =sinπ/7/(2sinπ/7) =1/2

蒲萱纨2963设函数f(x)=2sinxcos^2θ/2+cosxsinθ - sinx -
骆连缸19342245069 ______ f(x)=2sinxcos^θ/2+cosxsinθ-sinx =sinx(cosθ+1)+cosxsinθ-sinx =sinxcosθ+cosxsinθ+sinx-sinx =sin(x+θ) f(A)=sin(A+θ)=√3/2 所以A+θ=π/3或2π/3 由于0故θ =π/2 所以A=π/6 a/sinA=b/sinB B=π/4 所以C=7π/12