Find the exact value of .

MATHEMATICS · Single correct · AP · AP Precalculus · Trigonometric and Polar Functions · Trigonometric and Polar Functions

Problem

Find the exact value of

\cos\left(\pi+\dfrac{\pi}{6}\right)

. (a)

\dfrac{\sqrt{3}}{2}

(b)

-\dfrac{\sqrt{3}}{2}

(c)

-\dfrac{1}{2}

(d)

-\dfrac{\sqrt{2}}{2}