Question

copute the integrals
∫ pai cos(2x) dx

Answer 1

\[\int\limits_{}^{}\pi \cos2xdx \]
if u = 2x then:
du = 2dx
dx = du/2
\[\pi \int\limits_{}^{}cosu*\frac{ du }{ 2 } \]

\[\frac{ \pi }{ 2 }\int\limits_{}^{}cosudu \implies \frac{ \pi }{ 2 }sinu + C\]