sin^2B-sin^2C=√2/2sinAsinB,且a=√2/2b

在△ABC中,求证；sin^(A/2)+sin^(B/2)+sin^(C/2)=1-2sin(A/2)sin(B/2)sin(C/2） 在三角形ABC中sin^A+sin^B=2sin^C,则角C为? 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+sin^B)sin(A-B)=(sin^A-sin^B)sin(A+B) sin^A*(sin(A+B)-sin(A-B))=sin^B*(sin(A-B)+sin(A+B)) sin^A*2c 【证明】Sin A+sin B=2Sin 22 sin^2A+sin^2B=sin^2C求证△ABC的形状 sin^2 A=sin^2 B+sinBsinC+sin^2 C 求A角 证明 SIN²A+SIN²B-SIN²C=2SINASINBCOSC 证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b, 求证:sin(a+b)sin(a-b)=sin^2a-sin^2b 傅里叶级数作图f（x）=2sin[x] - sin[2x] + 2/3sin[3x] - 1/2sin[4x]我用mathematica输入程序Plot[{2sin[x],-2sin[x],2sin[x] - sin[2x],-2sin[x] + sin[2x],2sin[x] - sin[2x] + 2/3sin[3x],-2sin[x] + sin[2x] - 2/3sin[3x],2sin[x] - sin[2x] + 2/3si 求证(a^2+b^2-c^2)/(b^2+c^2-a^2)=(sin(A+B)+sin(A-B))/(sin(A+B)-sin(A-B)) 已知sin(a)=2sin(b)求sin(a/2)/sin(b/2)的值. △ABC中sin^2A-sin^2C=根号2sinAsinB-sin^2B+则角C为 在△ABC中 若sin^2A+sin^2B=2sin^2C 则∠C为? 在△ABC中,sin^2A+sinAsinB=sin^2C-sin^2B,则∠C= 证明cosA＋cosB＋cosC=1+4sin(A/2)sin(B/2)sin(C/2)证明：cosA＋cosB＋cosC=1+4sin(A/2)sin(B/2)sin(C/2)尽量详细一点选做cosA+cosB+cosC=1+4sin(A/2)sin(B/2)sin(C/2) cos(180-B-C)+cosB+cosC=1+2sin(A/2)[2sin(B/2)sin(C/2)] cos(180-B-C)+cosB+cosC 在三角形ABC中,sin^2A-sin^2C+sin^2B=sinAsinB,则角C为? 在三角形ABC 中,若sin A:sin B:sin C=3:2:4,则cos C的值