vector{AC}=(x_(C)-x_(A); y_(C)-y_(A))=(x_(C)-(-4); y_(C)-(-1))=(x_(C)+4; y_(C)+1)
По условию
vector{AC}=(5:5)
x_(C)+4=5 ⇒ x_(C)=5-4=1
y_(C)+1=5 ⇒ x_(C)=5-1=4
С(1;4)
Аналогично
vector{BD}=(x_(D)-x_(B); y_(D)-y_(B))=(3-x_(B); -4-y_(B))
По условию
vector{BD}=(4:-2)
3-x_(B)=4 ⇒ x_(B)=3-4=-1
-4-y_(B)=-2 ⇒ y_(B)=-4+2=-2
B(-1;-2)