Scrii ec dreptei BC
(y-1)/(-1-1)=(x+2)/(-3+2)
(y-!)/(-2)=(x+2)/(-1)
y-1=2x+4
y=2x+5=>
2x-y+5=0
Aplici formula formula distantei D de la un punct A la o dreapta BC
D(A;BC)=lAxo+Byo+cl/√(A²+B²)= unde A=2 B=-1 C=5 si xo=1 yo=3
D=l2*1-1*3+5l/√(4+1)=l2-3+5l/√5=4/√5=4√5/5