[tex]\qquad\qquad\huge\underline{{\sf Answer}}♨[/tex]
if the triangle is an Isosceles triangle, then it's other two angles measure 45° each.
So, let's use Trigonometry here :
[tex]\qquad \sf \dashrightarrow \: \cos(45) = \dfrac{10}{x} [/tex]
[tex]\qquad \sf \dashrightarrow \: \dfrac{1}{ \sqrt{2} } = \dfrac{10}{x} [/tex]
[tex]\qquad \sf \dashrightarrow \:x = 10 \sqrt{2} [/tex]
Therefore, the value of x is 10√2 units
