Evaluate (cos (frac{pi}{2} + frac{pi}{3}))
-
A.
(frac{-2}{sqrt{3}}) -
B.
(frac{-sqrt{3}}{2}) -
C.
(frac{sqrt{3}}{4}) -
D.
(frac{4}{sqrt{3}})
Correct Answer: Option B
Explanation
(cos (x + y) = cos x cos y – sin x sin y)
(cos (frac{pi}{2} + frac{pi}{3}) = cos frac{pi}{2} cos frac{pi}{3} – sin frac{pi}{2} sin frac{pi}{3})
= ((0 times frac{1}{2}) – (1 times frac{sqrt{3}}{2}))
= (0 – frac{sqrt{3}}{2} = -frac{sqrt{3}}{2})