Show that point A(-6,4)B(-13,4)C(-6,-3)D(-13,-3) are the vertices of a square
The equation of the line passing through the points A and B is , so this line is parallel to the x-axis.
The equation of the line passing through the points C and D is , so this line is parallel to the x-axis.
The equation of the line passing through the points B and D is , so this line is parallel to the x-axis.
The equation of the line passing through the points A and C is , so this line is parallel to the x-axis.
So
1) the line AB is parallel to the line CD and the line BD is parallel to the line AC, hence ABDC is a parallelogram,
2) the line AB is perpendicular to the line BD, hence ABDC is a rectangle,
3)
, so , hence ABDC is a rhombus.
ABCD is a square since it is a rhombus and a rectangle