Can you help me understand how to find the missing side?

Given the Right Triangle shown in the picture, you can find the missing side length "x" by applying the Pythagorean Theorem. This states that:
[tex]c^2=a^2+b^2[/tex]Where "c" is the hypotenuse (the longest side), and "a" and "b" are the legs of the Right Triangle.
In this case, you can set up that:
[tex]\begin{gathered} c=10 \\ a=6 \\ b=x \end{gathered}[/tex]Then, substituting values into the formula and solving for "x", you get:
[tex]\begin{gathered} 10^2=6^2+x^2 \\ 100=36+x^2 \\ 100-36=x^2 \end{gathered}[/tex][tex]\begin{gathered} 64=x^2 \\ \sqrt[]{64}=x \\ x=8 \end{gathered}[/tex]Hence, the answer is:
[tex]x=8[/tex]