To calculate the length between A and B you have to draw them in the cartesian system and link them with a line, then using that line as hypothenuse, draw a right triangle, whose base will be paralel to the x-axis and its height will be paralel to the y-axis.
Using the coordinates calculate the length of the base and height of the triangle:
Base= XA-XB= (-1)-(-8)=7
Height= YB-YA=7-(-7)=14
Now you have to apply pythagoras theorem you can calculate the length of the hypotenuse:
[tex]\begin{gathered} a^2+b^2=c^2 \\ c^2=7^2+14^2 \\ c^2=245 \\ c=\sqrt{245}=15.65 \end{gathered}[/tex]The distance between poins A and B is 15.65
