S=c²-a²-b²+2ab
=-(a²+b²-c²-2ab)
cosC=(a²+b²-c²)/2ab
S=2ab-2abcosC
=2ab(1-cosC)
=2a(2-a)(1-cosC)
=[-2(a-1)²+2](1-cosC)
cosC可以求出,a=1时最大,自己代一下吧
S=c²-a²-b²+2ab
=-(a²+b²-c²-2ab)
cosC=(a²+b²-c²)/2ab
S=2ab-2abcosC
=2ab(1-cosC)
=2a(2-a)(1-cosC)
=[-2(a-1)²+2](1-cosC)
cosC可以求出,a=1时最大,自己代一下吧