Integral minus phi sampai phi cos^2 x

jawab
integral 

(-pi ..pi)∫ cos² x dx

= (-pi...pi) ∫ 1/2 (cos 2x  + 1) dx

= [1/4 sin 2x + 1/2 x ](pi...-pi)

= 1/4 ( sin 2pi - sin (-2pi)) + 1/2 (pi - (-pi))

= 1/4 (sin 2pi + sin 2pi) + 1/2 (2 pi)

= 1/4 (0) + pi

= pi 

= 3,14