Question 325026
Use the distance formula,
{{{D^2=(x2-x1)^2+(y2-y1)^2}}}
{{{D^2=(2a-(-a))^2+(4b-b)^2}}}
{{{D^2=(3a)^2+(3b)^2}}}
{{{D^2=9a^2+9b^2}}}
{{{D=3sqrt(a^2+b^2)}}}