To express cos150° in surd form, we need to use the trigonometric identity cos(180° - θ) = -cos(θ).
Thus, cos150° = cos(180° - 30°) = -cos30°.
Using the value of cos30°, which is \(\frac{\sqrt{3}}{2}\), we get:
cos150° = -cos30° = -\(\frac{\sqrt{3}}{2}\)
Therefore, the correct answer is option B, \(-\frac{\sqrt{3}}{2}\).