If it's on the Cartesian plane, you find the difference between the x coordinates (let's call that value a), and you find the difference between the y coordinates (let's call that value b)
You square a and b, and add them together (to get [tex]a^2 + b^2[/tex])
You find the square root of the sum you attained and get:
[tex]\sqrt{a^2 + b^2}[/tex]= EF
