sin(A/2)

若sin^2a若sin^2a若sin^2a不等式两边同时加sin^2a可得：sin^2a+sin^2a2sin^2a|sina|3π/4+2kπ

sin^2(-a)化简sin^2(-a)化简sin^2(-a)化简∵sin(a)是奇函数,∴sin(-a)=-sin(a)∴sin²(-a)=sin²(a)=1-cos²

sin(arccos(2sin(a)))=sin(arccos(2sin(a)))=sin(arccos(2sin(a)))=sin(arccos(2sin(a)))=√(1-4sin²a)

【证明】SinA+sinB=2Sin22【证明】SinA+sinB=2Sin22【证明】SinA+sinB=2Sin22应该是sinA+sinB=2sin[(A+B)/2]cos[(A-B)/2]A=

证明sin(a+b)sin(a-b)=sin^2a-sin^2b,证明sin(a+b)sin(a-b)=sin^2a-sin^2b,证明sin(a+b)sin(a-b)=sin^2a-sin^2b,左

求证:sin(a+b)sin(a-b)=sin^2a-sin^2b求证:sin(a+b)sin(a-b)=sin^2a-sin^2b求证:sin(a+b)sin(a-b)=sin^2a-sin^2bs

sina+sin2a+sin3a+...+sinna怎么求和?sina+sin2a+sin3a+...+sinna怎么求和?sina+sin2a+sin3a+...+sinna怎么求和?利用积化和差公

sina+sin2a+sin3a+...+sinna怎么求和?sina+sin2a+sin3a+...+sinna怎么求和?sina+sin2a+sin3a+...+sinna怎么求和?采用复数解法：

已知sin(a)=2sin(b)求sin(a/2)/sin(b/2)的值.已知sin(a)=2sin(b)求sin(a/2)/sin(b/2)的值.已知sin(a)=2sin(b)求sin(a/2)/

求证1+sina+cosa+2sinacosa/1+sina+cosa=sina+cosa求证1+sina+cosa+2sinacosa/1+sina+cosa=sina+cosa求证1+sina+c

化简:sin(-a)cos(2π+a)sin(-a-π)化简:sin(-a)cos(2π+a)sin(-a-π)化简:sin(-a)cos(2π+a)sin(-a-π)-sinacosasina=-s

化简SinA+Sin2A/1+cosA+化简SinA+Sin2A/1+cosA+化简SinA+Sin2A/1+cosA+分子=sinA+sin2A=sinA+2sinAcosA=sinA*(1+2co

化简sin^(a-30°)+sin^(a+30°)-sin^a化简sin^2(a-30°)+sin^2(a+30°)-sin^2a化简sin^(a-30°)+sin^(a+30°)-sin^a化简si

sin2a+2sin方a/1+tana=2sinacosasin2a+2sin方a/1+tana=2sinacosasin2a+2sin方a/1+tana=2sinacosa证：sin2a=2sina

求证:sin2a/1+sina+cosa=sina+cosa-1急求证:sin2a/1+sina+cosa=sina+cosa-1急求证:sin2a/1+sina+cosa=sina+cosa-1急s

3在三角形ABC中,已知（a2+b2）sin（A-B）=（a2-b2）sin(A+B)求证：ABC是等腰或直角三角形(a^2+b^2)sin(A-B)=(a^2-b^2)sin(A+B),(sin^A

(cosa)^4+(sina)^2*(sina)^2+(sina)^2=?(cosa)^4+(sina)^2*(sina)^2+(sina)^2=?(cosa)^4+(sina)^2*(sina)^2

cosA+cos^2A=1,sin^2A+sin^4A+sin^8AcosA+cos^2A=1,sin^2A+sin^4A+sin^8AcosA+cos^2A=1,sin^2A+sin^4A+sin^

(1-sin^6a-cos^6a)/(sin^2a-sin^4a)(1-sin^6a-cos^6a)/(sin^2a-sin^4a)(1-sin^6a-cos^6a)/(sin^2a-sin^4a)分

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)懂得进.证明,sina+sin(a+b)+si