kX81be
Written on June 24, 2019
% Dans le préambule
% -----------------
\usepackage{amsmath}
% -----------------
\begin{align*}
\int_0^\pi\sin^2(t) dt
&=\int_0^\pi \frac{1-\cos(2t)dt}{2} \\
&=\left[
\frac{1}{2} (t-\sin(t)\cos(t))
\right]_0^\pi \\
&=\frac{\pi}{2}
\end{align*}