Question

Distance between (0,2) and (0,4)

Answer 1

D= √(x sub2 - x sub1)^2 + (y sub2 - ysub1)

D= √(0-0)^2 + (4-2)^2

D= √0^2 + 2^2

D= √0 + 4

D= √4

D = 2

Answer 2

There are many ways to do this, I prefer the distance formula it looks like this:
$\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$
We are given 2 pairs of coordinates: (0,2) and (0,4) 
0=x1
2=y1
0=x2
4=y2
We take the numbers and sub in the values above in place of the variables:
  $\sqrt{(0-0)^2+(4-2)^2}$
Simplfy it: 
$\sqrt{(0)^2+(2)^2}$
0^2=0
2^2=4
We are left with :
$\sqrt{4}$
$\sqrt{4} =2$
Final answer: 2