Réponse :
Explications étape par étape :
■ exo 6 :
D = cos(2,5π - x) = cos(π/2 - x) = sinx .
E = sin(x + 100π) = sinx .
F = sin(x + 71π) = sin(x + π) = -sinx .
G = cos(x - 78π) = cosx .
H = cos(1008π + x) = cosx .
J = sin(π/2 + x) = cosx .
K = cos(π/2 - x) - 4sin(x + π/2) - 5sin(π + x)
= sinx - 4cosx + 5sinx = 6sinx - 4cosx .
L = sin(x + π/2) - 2cos(x + π) - 5sinx
= cosx + 2cosx - 5sinx = 3cosx - 5sinx .
■ exo 7 :
1°) angle cherché = -π/3 = -60°
2°) angle = -π/4 = -45°
3°) angle = -5π/6 = -150° OU angle = 7π/6 = 210° .
4°) angle = -π/2 = -90° OU angle = 1,5π = 270°
