The formula of a distance between two points A and B is :
[tex] AB=\sqrt{(x_{B}- x_{A})^2 +( y_{B}- y_{A})^2 } [/tex]
You should this formula by heart.
Then, you just have to apply it ! :D
Here :
[tex] x_{A}=-5 [/tex]
[tex] y_{A} =0[/tex]
[tex] x_{B} =-4[/tex]
[tex] y_{B}= 1[/tex]
Therefore :
[tex] \sqrt{(-4-(-5))^2+(1-0)^2} [/tex]
[tex]= \sqrt{1^2+1^2} [/tex]
[tex]= \sqrt{1+1} [/tex]
[tex]= \sqrt{2} [/tex]
In short, the answer would be the first option : [tex] \sqrt{2} [/tex].
Hope this helps !
Photon
