b/a=根号2 b=√2a
代入b2+c2-根号3ab=a2
2a²+c²-√6a²=a²
c²=(√6-1)a²
由余弦定理cosC=(a²+b²-c²)/(2ab)
=(a²+2a²-√6a²+a²)/(2√2a²)
=(4-√6)/(2√2)
=√2-√3/2
所以C=arc cos(√2-√3/2)
希望能帮到你O(∩_∩)O