Answer:
It is actually very simple:
Notice that they don't actually do the square of 49 and 64. For some reason, they do the square root of the values without squaring them. If we were to do it in the right way, the answer would be:
[tex]49^{2} +64^{2} = c^{2}[/tex]⇔ 2401+4096 = [tex]c^{2}[/tex] ⇔ 6497 = [tex]c^{2}[/tex] ⇔ [tex]\sqrt{6497}[/tex] = [tex]\sqrt{c^{2} }[/tex] ⇔ 80,6 ≈ c
I believe this is the answer. I hope I had helped :)
