\int_{0}^{π} c o s (t) d t = s i n (t) {∣ ∣ ∣}_{0}^{π} = s i n (π) - s i n (0) = 0

${ \int_0^\pi cos(t)\, dt = sin(t) \bigg |_0^\pi = sin(\pi) - sin(0) = 0}$