First, let´s calculate the length of the sides of the triangle, by calculating the distance between the given points.
Use the following formula:
where (x1,y1) and (x2,y2) are the limits of a segment with length d.
Then, the ditance between points X and Y is;
The distance between points Y and Z is:
and the distance between points Z and X is:
Then, you have two sides with the same length, which are sides XY and YZ and another side with a different length.
When a triangle has two sides with the same length, such a triangle is isosceles.