since there are 3 lines (triangle), perimeter is simply the sum of those sides
find each side using distance (d) formula:
[tex](d) = \sqrt{( {(x2 - x1)}^{2} + {(y2 - y1)}^{2} )} [/tex]
where two points of the line lie at (x1, y1) and (x2, y2)
let's name the points of our triangle to make it easier: A = (8, 2), B = (8, 6), C = (6, 6)
[tex]d(ab) = \sqrt{( {(8 - 8)}^{2} + {(6 - 2)}^{2} )} \\ = \sqrt{ {4}^{2} } = 4[/tex]
[tex]d(bc) = \sqrt{( {(6 - 8)}^{2} + {(6 - 6)}^{2})} \\ = \sqrt{{2}^{2} } = 2[/tex]
[tex]d(ac) = \sqrt{( {(6 - 8)}^{2} + {(6 - 2)}^{2} )} \\ = \sqrt{( {2}^{2} + {4}^{2}) } = \sqrt{(4 + 16)} \\ = \sqrt{20} = 2 \sqrt{5} = 4.47[/tex]
So now for P add AB + BC + AC = 4+2+4.47
P = 10.47 units squared
