Answer:
solution,
Let the points be A and B
A(-4,-8)--->(X1,y1)
B(-4,12)---->(x2,y2)
Now,
[tex]ab = \sqrt{ {(x2 - x1)}^{2} + {(y2 - y1)}^{2} } \\ \: \: \: = \sqrt{ {( - 4 - ( - 4)}^{2} + 12 - ( - 8) ^{2} } \\ \: \: \: \: = \sqrt{ {( - 4 + 4)}^{2} + {(12 + 8)}^{2} } \\ = \: \: \: \: \sqrt{ {(0)}^{2} + {(20)}^{2} } \\ \: \: \: \: = \sqrt{0 + 400} \\ \: \: \: = \sqrt{400} \\ \: \: = \sqrt{ {(20)}^{2} } \\ \: \: = 20 \: units[/tex]
Hope this helps..
Good luck on your assignment...