To find the missing side \( x \) of a right triangle, you can use the Pythagorean theorem, which states:
\[ a^2 + b^2 = c^2 \]
where \( c \) is the length of the hypotenuse (the side opposite the right angle), and \( a \) and \( b \) are the lengths of the other two sides.
If you provide the lengths of the two known sides of the triangle, I can help you calculate the missing side \( x \). Please let me know the values.