Use a suitable change of variables (substitution) to evaluate the integral: ∫2.5tsin(81t²)cos(81t²)dt. Which of the following options gives the correct result? A) (5sin(81t²)²)/(648)+C B) (5sin(81t²)²)/(648) C) (5sin(81t²)²)/(648) + D) None of the above. Please help with the formulas.
