What is the value of pq ?
Consider the following for the next two (02) items that follow : Let p=\cos\left(\frac{\pi}{5}\right)\cos\left(\frac{2\pi}{5}\right) and q=\cos\left(\frac{4\pi}{5}\right)\cos\left(\frac{8\pi}{5}\right).
- A. -\frac{1}{16} ✓
- B. -\frac{1}{4}
- C. \frac{1}{4}
- D. \frac{1}{16}
Correct Answer: A. -\frac{1}{16}
Explanation
From the evaluation in the previous part, p = \frac{1}{4} and q = -\frac{1}{4}. The product pq = \left(\frac{1}{4}\right)\left(-\frac{1}{4}\right) = -\frac{1}{16}.