Réponse :
1) calculer l'angle ^XOY dans des cas suivants:
a) cos ^XOY = 1/3 ⇒ ^XOY = arccos(1/3) = cos⁻¹(1/3) = 70.53°
b) cos ^XOY = 0 ⇒ ^XOY = arccos(0) = cos⁻¹(0) = 90°
c) cos ^XOY = 1/4 ⇒ ^XOY = arccos(1/4) = cos⁻¹(1/4) = 75.52°
d) cos ^XOY = 1/2 ⇒ ^XOY = arccos(1/2) = cos⁻¹(1/2) = 60°
e) cos ^XOY = 3/4 ⇒ ^XOY = arccos(3/4) = cos⁻¹(3/4) = 41.41°
2) donner un arrondi à 0.001 près de
cos 9° = 0.388
cos 88 = 0.035
cos 1° = 0.999
cos 44° = 0.719
EX2
1) calculer CB
cos ^C = CB/AC = 0.6 ⇒ CB = AC x cos ^C = 4 x 0.6 = 2.4 cm
2) calcule FE
cos ^F = FE/DF ⇒ FE = DF x cos ^F = 10 x cos 35° = 10 x 0.819 = 8.19 cm
3) calcul LJ
cos 65° = KJ/LJ ⇒ LJ = KJ/cos 65° = 8/0.423 = 18.91 cm
Explications étape par étape
