jika vektor a=(-2,4,4) dan b=(-6,3,-2), besar sudut vektor antara a dan b

a.b = 12 + 12 -8 = 16
|| a || = √(4+16+16) = √36 = 6
|| b || = √36+9+4 = √49 = 7

cos teta = (a.b)/(|| a || . || b ||)
cos teta = 16/42
cos teta = 8/21
teta = cos^-1 8/21
teta = 1,18°

Sudutnya adalah 1,18°