证明(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2=3/2
来源：学生作业帮助网 编辑：六六作业网 时间：2024/11/08 16:48:25
证明(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2=3/2证明(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2=3/2证明(sinA)
证明(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2=3/2
证明(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2=3/2
证明(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2=3/2
证明：因为(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2
=(sinA)^2+[sinAcos120度+sin120度cosA]^2+[sinAcos120度-sin120度cosA]^2
=(sinA)^2+2(sinAcos120度)^2+2(sin120度cosA)^2
=(sinA)^2+2(-1/2sinA)^2+2(√3/2cosA)^2
=(sinA)^2+1/2(sinA)^2+3/2(cosA)^2
=3/2(sinA)^2+3/2(cosA)^2
=3/2[(sinA)^2+(cosA)^2]
因为(sinA)^2+(cosA)^2=1
所以原式=3/2[(sinA)^2+(cosA)^2]=3/2
]
证明sin^2a+sin^2β+1>sina*cosa+sina+sinβ
证明sinA+sin(A+2π/3)+sin(A-2π/3)=0
证明sinA+sin(A+2π/3)+sin(A-2π/3)=0
怎么证明2sinA*cosA=sin(2A)
证明sin(2a+b)/sina-2cos(a+b)=sinb/sina
证明sin(2a+b)/sina-2cos(a+b)=sinb/sina
证明sina sin(a+2b) - sinb sin(b+2a) =sin(a+b)sin(a-b)
证明(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2=3/2
证明根号3sina-cosa=2sin(a-π/6)
sinA+sin(90°-A)+1/sinA-sin(90°-A)+1=cot(A/2) 请问这怎么证明,
证明：[sin(a-60)]^2+[sina]^2+[sin(a+60)]^2=3/2
证明三角函数等式sin(A+B)-sinA=2cos(A+B/2)sin(B/2)
sina(cosa)^3=1/4sin 2a+1/8sin 4a证明过程
1- sin(2π/3 - a)/sina
懂得进.证明,sina+sin(a+b)+sin(a+2b)+...sin(a+nb)=sin(a+ab/2)sin[(n+1)b/2]/sin(b/2)
sin(a-2π)*sin(π+a)为什么等于sina(-sina)啊……
sin(2π+a) ,sin(π+a),sin(5π+a) 的区别为什么sin(2π+a) =sina sin(π+a)=-sina
如何证明sinA+sinB=2sin((A+B)/2)cos((A-B)/2)