If $f(x) = \cos([\pi^2]x) + \cos([-\pi^2]x)$, where $[\ ]$ denotes the greatest integer function, then the value of $f(\pi/2)$ is
- A. -1
- B. 0
- C. 1
- D. 2
✅ Correct Answer: -1
Explanation
$\pi^2 = 9.85$ approximately So $[\pi^2]=9$ and $[-\pi^2]=-10$ $f(x) = \cos(9x) + \cos(10x)$ $f(\pi/2) = \cos(9\pi/2) + \cos(5\pi)$ $= 0 - 1 = -1$
🎯 Happy Preparation — ACME Academy
