we are talking about a right triangle so the phytagoras equation can be used:
[tex] a^{2} + b^{2} = c^{2} [/tex]
[tex] 6^{2} + 6^{2} = 36 + 36 = 72 = c^{2} [/tex]
[tex] \sqrt{ c^{2} } = \sqrt{72} =8.48528...[/tex]
So the hypothinus is equal to approximately 8.49