Exercice

Simplifier le plus possible : A = cos π + cos 3 π 4 + cos π 2 + cos π 4

A = cos π + cos 3 π 4 + cos π 2 + cos π 4 = 1 2 2 + 0 + 2 2 = 1

B = cos 0 + cos π 4 + cos π 2 + cos 3 π 4 + cos π

B = cos 0 + cos π 4 + cos π 2 + cos 3 π 4 + cos π = 1 + 2 2 + 0 2 2 1 = 0