s = 1/2 ab sinC = 1/2ab 根号3 / 2 = 根号3 ab = 4 cos C = (a^2+b^2-c^2) / (2ab) = 1/2 a^2+b^2 = 8 a = 2, b = 2 sin B = 2 sin A a / sinA = b / sin B a = b/2 cos C = (a^2+b^2-c^2) / (2ab) = 1/2 a= 2根号3 / 3 b = 4根号3 / 3 s = 1/2 ab sinC = 2根号3 / 3
s = 1/2 ab sinC = 1/2ab 根号3 / 2 = 根号3 ab = 4 cos C = (a^2+b^2-c^2) / (2ab) = 1/2 a^2+b^2 = 8 a = 2, b = 2 2)由B=120-A代入sinB=2sinA 整理得:cosa/2=√3/2*sina ==>移项整理得:sin(a-π/6)=0,...