Find value of X in the isosceles triangle shown below

Answer:
A
Step-by-step explanation:
You have to use Pythagorean theorem.
a^2 + b^2 = c^2
x^2 + 3^2 = 5^2 (you know that b=3 because is the half of 6)
x^2 + 9 = 25
x^2 = 25 - 9
x^2 = 16
x = √16
x = 4