8+-4sqrt(3)/2
Aziz has foundand approximation. Is that what you wanted? Perhaps you just wanted it simplified.
$$8\pm \frac{4\sqrt3}{2}\\\\ =8\pm 2\sqrt3\\\\\ or \\\\ =4(2\pm \sqrt3)$$
8 + (-4sqrt(3)/2) = 4.5358983848622454.