( 28182 : 7 ) * 6 = 24156
m = 2 5/35 + 7 1/9
2 5/35 = 2 1/7 = 15/7
7 1/9 = 64/9
135/63 + 448/63 = (135 + 448)/63 = 583/63 = 9 16/63
99:31=3(ост.6)
31 ×3=93
99-93=6
Найдем координаты соответствующих векторов
АВ = (3-6; 3-7) = (-3 ; -4)
|AB| =
AC (1-6 ; -5-7) = (-5; -12)
|AC| =
AB*AC = (-3)*(-5) + (-4)*(-12) = 15+48 = 63
cosA =
BA = (3; 4) |BA| = 5
BC = (-2; -8) |BC| =
BA*BC = -6 -32 = -38
cos B =
CA = (5; 12) CB (2; 8) |CB| = CA =13
cosC =