Formula generala pentru distanta a doua drepte:
[tex]\boxed{CD= \sqrt{(x_{D}-x_C)^2+(y_D-y_C)^2 } }[/tex]
[tex]CD = \sqrt{(4-x)^2+(-1-3)^2} = \sqrt{16-8x+x^2+16}= \sqrt{x^2-8x+32}\\[/tex]
[tex]\sqrt{x^2-8x+32} = 4\sqrt{5} \\x^2-8x+32 = 16*5 \\x^2-8x+32-80=0 \\x^2-8x-48=0 \\delta = 64+192 = 256\\x_1 = \frac{8+16}{2} =12\\x_2 = \frac{8-16}{2} = -2[/tex]
x = {-2, 12}
