ϑ=arccos U⋅V |U|⋅|V| MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGe aGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaq Fn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpe WZqaaeaaciWacmGadaGadeaabaGaaqaaaOqaaiabeg9akjabg2da9i aabggacaqGYbGaae4yaiaabogacaqGVbGaae4CamaalaaabaGaaCyv aiabgwSixlaahAfaaeaadaabdaqaaiaahwfaaiaawEa7caGLiWoacq GHflY1daabdaqaaiaahAfaaiaawEa7caGLiWoaaaaaaa@4BED@
NOTE L'angle de deux vecteurs est toujours défini puisque le produit scalaire vérifie l'inégalité | U⋅V|≤|U|⋅|V| MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGe aGqk0di9Wr=fpeei0di9v8qiW7rqqrVepeea0xe9LqFf0xc9q8qqaq Fn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpe WZqaaeaaciWacmGadaGadeaabaGaaqaaaOqaamaaemaabaGaaCyvai abgwSixlaahAfaaiaawEa7caGLiWoacqGHKjYOdaabdaqaaiaahwfa aiaawEa7caGLiWoacqGHflY1daabdaqaaiaahAfaaiaawEa7caGLiW oaaaa@4BF6@ .