SinC/c = SinA/a;
2acos(π/3+C) = a*CosC-2a*Sin(π/3)*SinC=a*CosC-2c*Sin(π/3)*SinA;
余弦定理得 CosC=(a^2+b^2-c^2)/2ab
因此 b-c=(a^2+b^2-c^2)/2b-2c*Sin(π/3)*SinA;
(b^2+c^2-a^2)/2bc + 2*Sin(π/...
SinC/c = SinA/a;
2acos(π/3+C) = a*CosC-2a*Sin(π/3)*SinC=a*CosC-2c*Sin(π/3)*SinA;
余弦定理得 CosC=(a^2+b^2-c^2)/2ab
因此 b-c=(a^2+b^2-c^2)/2b-2c*Sin(π/3)*SinA;
(b^2+c^2-a^2)/2bc + 2*Sin(π/...