Simplified to a2+b2=c2,
In other words, the square of the hypotenuse of a right triangle is equal to the sum of the squares of two right angles.
(2) As shown:
From the figure, we can get (a+b) 2 = C2+4× 12ab.
So A2+B2 = C2.
(3)c2=a2+b2=(a+b)2-2ab=49-24=25,
∴c=5.