(a^2+b^2-c^2)^2-4a^2b^2
=(a^2+b^2-c^2+2ab)(a^2+b^2-c^2-2ab)
=[(a+b)^2-c^2][(a-b)^2-c^2]
=(a+b+c)(a+b-c)(a+c-b)(a-b-c)
a+b>c a+c>b b+c>a
(a^2+b^2-c^2)^2-4a^2b^2
(a^2+b^2-c^2)^2-4a^2b^2
=(a^2+b^2-c^2+2ab)(a^2+b^2-c^2-2ab)
=[(a+b)^2-c^2][(a-b)^2-c^2]
=(a+b+c)(a+b-c)(a+c-b)(a-b-c)
a+b>c a+c>b b+c>a
(a^2+b^2-c^2)^2-4a^2b^2