Evaluate \(\cos (\frac{\pi}{2} + \frac{\pi}{3})\)
Take Free Practice Test On 2026 JAMB UTME, Post UTME, WAEC SSCE, GCE, NECO SSCE
Correct Answer: Option B
Explanation:
\(\cos (x + y) = \cos x \cos y - \sin x \sin y\)
\(\cos (\frac{\pi}{2} + \frac{\pi}{3}) = \cos \frac{\pi}{2} \cos \frac{\pi}{3} - \sin \frac{\pi}{2} \sin \frac{\pi}{3}\)
= \((0 \times \frac{1}{2}) - (1 \times \frac{\sqrt{3}}{2})\)
= \(0 - \frac{\sqrt{3}}{2} = -\frac{\sqrt{3}}{2}\)
\(\cos (x + y) = \cos x \cos y - \sin x \sin y\)
\(\cos (\frac{\pi}{2} + \frac{\pi}{3}) = \cos \frac{\pi}{2} \cos \frac{\pi}{3} - \sin \frac{\pi}{2} \sin \frac{\pi}{3}\)
= \((0 \times \frac{1}{2}) - (1 \times \frac{\sqrt{3}}{2})\)
= \(0 - \frac{\sqrt{3}}{2} = -\frac{\sqrt{3}}{2}\)