What is the perimeter of a triangle with corners at #(3 ,6 )#, #(1 ,8 )#, and #(8 ,7 )#?
So the first pair between (3,6) and (1,8) is
Second is the pair of points (1,8) and (8,7). Plug this in once again for
Finally for the third pair of points, (8,7) and (3,6) you plug it in for
Now simply the radicals as much as you can.
Now you just add like terms and thats it so in the end you get