In the \(xy\)-plane, an equilateral triangle has vertices at \((0, 0)\) and \((9, 0).\) What could be the coordinates of the third vertex?
(A) \((0, 4.5)\)
(B) \((4.5, 4.5)\)
(C) \(\left(\dfrac{9\sqrt3}2, \dfrac{9\sqrt3}2\right)\)
(D) \((4.5, 9\sqrt3)\)
(E) \(\left(4.5, \dfrac{9\sqrt3}2\right)\)
Answer: E
Source: Manhattan GMAT