Help quickly! Please find X

Answer:
About 4.5
Step-by-step explanation:
Since the full base has length 8, half of it must have length 4. Now, using the Pythagorean theorem, you can find x:
[tex]x=\sqrt{6^2-4^2}=\sqrt{36-16}=\sqrt{20}\approx 4.5[/tex] or answer choice D
Hope this helps!