Находим координаты векторов:
AB={2-3, 2-(-1) } ={-1,3}
CD={-1-1, -2 - (-3)} ={-2,1}
DB={2-(-1), 2-2} ={3,0}
AC={1--3, -3-(-1)} ={-2,-2}
(AB - CD) = {-1 - (-2), -2-1} = {1, -3}
(DB + AC) = {3 + (-2), 0+(-2} = {1, -2
F = (AB - CD)*(DB + AC) = 1*1 + (-3)*(-2) = 1 + 6 =7
Находим координаты векторов:
AB={2-3, 2-(-1) } ={-1,3}
CD={-1-1, -2 - (-3)} ={-2,1}
DB={2-(-1), 2-2} ={3,0}
AC={1--3, -3-(-1)} ={-2,-2}
(AB - CD) = {-1 - (-2), -2-1} = {1, -3}
(DB + AC) = {3 + (-2), 0+(-2} = {1, -2
F = (AB - CD)*(DB + AC) = 1*1 + (-3)*(-2) = 1 + 6 =7