Part 1
Using the distance formula,
[tex]AB=\sqrt{(-2-1)^{2}+(2-7)^{2}}=\sqrt{34}\\\\BC=\sqrt{(-2-4)^{2}+(2-2)^{2}}=6\\\\AC=\sqrt{(1-4)^{2}+(7-2)^{2}}=\sqrt{34}[/tex]
So, the measure of the longest side is 6 units.
Part 2
Triangle ABD will have vertices A(1,7), B(-2, 2), and D(1,2).
We already know that [tex]AB=\sqrt{34}[/tex]
Using the distance formula,
[tex]AD=\sqrt{(1-1)^{2}+(7-2)^{2}}=5\\\\BD=\sqrt{(-2-1)^{2}+(2-2)^{2}}=3[/tex]
So, ABD is a scalene triangle.
Part 3
From part 2, we know that the length of side AD is 5 units.
