Question 778595
The distance is given be
{{{d = sqrt((Xa-Xb)^2+(Ya-Yb)^2)}}}
{{{d = sqrt(((a+1)-(a-1))^2+((2a+3)-(2a-1))^2)}}}
{{{d = sqrt(2^2+4^2)}}}
{{{d = sqrt(4+16)}}}
{{{d = sqrt(20)}}}
{{{d = 2sqrt(5)}}}