It depends on what type of Triangle or what the volume or area is. This question is missing information.
The point of inflection is calculated by equating the second derivative to zero and determining x from there.
f"(x) = -x²2xsinx² + cosx²(2x) = 0
2xcosx² - 2x³sinx² = 0
2x (cosx² - xsinx²) = 0
2x = 0 ⇒ x = 0
cosx² - xsinx² = 0 ⇒ x = 3.82 (if you use shift+solve in your scientific calculator)
Thus, the function only has 1 point of inflection and it is at x = 0.
The answer to your question is 81,300.