Formulaire de Trigonométrie
K
cotan(x)
B
M H
sin(x)
x
cos(x) = abscisse de M
tan(x)
sin(x) = ordonnée de M
1 cos(x) A
tan(x) = AH cotan(x) = BK eix = zM
sin(x) cos(x) π
1
π
+ πZ, tan(x) = et pour x ∈ πZ, cotan(x) =
/
. Enfin pour x ∈ Z, cotan(x) =
/
.
2
cos(x) sin(x) 2 tan(x) Valeurs usuelles.
Pour x ∈
/
x en
◦
x en rd
0
30
45
60
90
0
π
6
π
4
π
3
√
3
2
π
2
sin(x)
0
cos(x)
1
tan(x)
0
cotan(x)
√
1
2
√ =
2
2
√
1
2
√ =
2
2
1
2
√
3
2
∞
1
√
3
√
3
1
1
1
2
√
3
1
√
3
1
0
∞
0
∀x ∈ R, cos2 x + sin2 x = 1
1
π
.
∀x ∈ + πZ, 1 + tan2 x =
/
2 cos2 x
1
.
∀x ∈ πZ, 1 + cotan2 x =
/
sin2 x addition d’un tour
addition d’un demi-tour
angle opposé
angle supplémentaire
cos(x + 2π) = cos x sin(x + 2π) = sin x tan(x + 2π) = tan x cotan(x + 2π) = cotan x
cos(x + π) = − cos x sin(x + π) = − sin x tan(x + π) = tan x cotan(x + π) = cotan x
cos(−x) = cos x sin(−x) = − sin x tan(−x) = − tan x cotan(−x) = − cotan x
cos(π − x) = − cos x sin(π − x) = sin x tan(π − x) = − tan x cotan(π − x) = − cotan x
angle complémentaire π cos( − x) = sin x
2
π sin( − x) = cos x
2
π tan( − x) = cotan x
2
π cotan( − x) = tan x
2
quart de tour direct π cos(x + ) = − sin x
2
π sin(x + ) = cos x
2
π tan(x + ) = − cotan x
2
π cotan(x + ) = − tan x
2
quart de tour indirect π cos(x − ) = sin x
2
π sin(x − ) = − cos x
2
π tan(x − ) = − cotan x
2
π cotan(x − ) = − tan x
2
c Jean-Louis Rouget, 2008. Tous droits réservés.
1
http ://www.maths-france.fr
Formules d’addition
Formules de duplication
cos(a + b) = cos a cos b − sin a sin b cos(a − b) = cos a cos b + sin a sin b sin(a + b) = sin a cos b + sin b cos a sin(a − b) = sin a cos b − sin b cos a
cos(2a) = cos2 a − sin2 a
= 2 cos2 a − 1
= 1 − 2 sin2 a sin(2a) = 2 sin a cos a