bonsoir
1)
(sin x+1)(cos x-1) = 0
=> sinx +1 =0
ou
cosx -1 =0
sin x= -1
sin x = sin (-π/2)
x= -π/2 +2kπ avec k €Z
cos x= 1
cosx= cos 0
x= 0 + 2kπ avec k €Z
S={-π/2 +2kπ ; 0 +2kπ }
2)
cos 4x = -1
cos4x=cos π
4x= π +2kπ
x =π/4 +(2/4) kπ = π/4 +kπ /2
4x= -π+2kπ
x= - π/4 +(2/4) kπ =- π/4 +kπ /2
S={-π/4 +kπ/2 ; π/4 +2kπ/2}
3)
sin 2x= -1/2
sin 2x= sin( -π/6)
2x= -π/6 +2kπ
ou
2x = π- (-π/6) +2kπ
x= -π/12 +kπ
ou
x=7π/12 +kπ
S={-π/12 +kπ ; 7π/12 + kπ } avec k €Z
