because you end with /math, not \math.

What do you want? If you know the answer is 6, then you know your answer is wrong. If you want us to check your work and seeAND

The answer i have been obtaining is a=4

The formula to use was d = \sqrt(x2-x1)^2+(y2-y1)^2

in this case d being \sqrt 41

the actual answer is a= 6..whereyou went wrong, you will need to show your work!