Answer:
Square
Step-by-step explanation:
There are different types of quadrilateral,
Kite : a quadrilateral which has two pairs of adjacent equal sides,
Rectangle : a quadrilateral which has two pairs of opposite equal sides and 4 right angles,
Rhombus : a quadrilateral which has equal sides with two pairs of equal opposite angles,
Square : a quadrilateral which has equal sides with 4 right angles,
Trapezoid : a quadrilateral which has one pairs of opposite parallel sides,
Let A≡(1,3), B≡(7,-3), C≡(1,-9) and D≡(-5,-3),
By Distance formula,


Similarly,



Now, the slope of AB,

Similarly,
The slope of BC,

Since, 
Hence, ∠B = 90°,
Similarly, We can obtain,
∠A = ∠C = ∠D = 90°
Therefore, By the above definitions it is clear that ABCD is a square.