Answer:
The slope of AB is - 2,
Slope of BC is 
Slope of CD is 
Slope of AD is
,
ABCD is trapezoid because one pair of opposite sides is parallel.
Step-by-step explanation:
Given vertices of quadrilateral ABCD,
A(−1, −1) , B(−3, 3) , C(1, 5) , and D(5, 2),
∵ Slope of a line passes through two points
and
is,

Thus, the slope of AB = 
Slope of BC = 
Slope of CD = 
Slope of DA = 
Since, when two line segment having the same slope then they are parallel to each other.
∴ BC ║ DA
A quadrilateral only having two parallel sides is called trapezoid,
Hence, ABCD is a trapezoid.