Answer:
Since there is a right angle, this is a right-angled triangle and we can solve for x using Pythagoras Theorem that goes [tex]a^2+b^2=c^2[/tex], where c is the hypotenuse (longest side of the triangle).
In this case, x would be the c.
Substitute in values of a and b:
[tex]10^2+10^2=c^2[/tex]
[tex]c^2=200[/tex]
[tex]c=\sqrt{200}[/tex]
[tex]c=10\sqrt{2}[/tex] (Option A)
