Question

Calcule o valor de a sabendo que a distância entre A( 2, a ) e B( 1, -4 ) é igual a 1.

Answer 1

$d^2=(x_b-x_a)^2+(y_b-y_a)^2\\\\ 1^2=(1-2)^2+(-4-a)^2\\\\ 1 = (-1)^2+(-a-4)^2\\\\ 1=1+a^2+8a+16\\\\ a^2+8a+16=0\\\\ \Delta=64-64\\\\ \Delta=0\\\\ a'=-4\\ a''=-4\\\\ \boxed{S=(-4)}$