The answer is 6
First, you must put the values in the formula.
[tex]a^2+b^2=c^2[/tex]
[tex]a^2+8^2=10^2[/tex]
Then, you must simplify the exponents.
[tex]a^2+64=100[/tex]
Next, subtract 64 on both sides.
[tex]a^2+36[/tex]
Finally, eliminate exponents.
[tex]\sqrt{a^2}=\sqrt{36}[/tex]
[tex]a=6[/tex]