Question

Lungimea segm avand capetea(1,2)si (b(2,-1 ).

Answer 1

$AB^2=(x_B-x_A)^2+(y_B-y_A)^2=(2-1)^2+(-1-2)^2=1^2+(-3)^2=1+9=10 \\ \\ AB=\sqrt{10}$