23*(-5)-(-3)除3/128

23*(-5)-(-3)除3/128
23*(-5)-(-3)除3/128

23*(-5)-(-3)除3/128
=-23×5+3×128/3
=-115+128
=13

23*(-5)-(-3)除3/128
=-115+128
=13

c最大
所以角C最大
cosC=(a²+b²-c²)/2ab
=(1+4-6)/(2*1*2)
=-1/4
cosB=√3/2=(a²+c²-b²)/2ac=(a²+27-9)/(6a√3)
a²+18=9a
(a-3)(a-6)=0
所以a=3,a=6