Answer18:
The quadrilateral ABCD is not a parallelogram
Answer19:
The quadrilateral ABCD is a parallelogram
Step-by-step explanation:
For question 18:
Given that vertices of a quadrilateral are A(-4,-1), B(-4,6), C(2,6) and D(2,-4)
The slope of a line is given m=
Now,
The slope of a line AB:
m=
m=
m=
The slope is 90 degree
The slope of a line BC:
m=
m=
m=
The slope is zero degree
The slope of a line CD:
m=
m=
m=
The slope is 90 degree
The slope of a line DA:
m=
m=
m=
m=
The slope of the only line AB and CD are the same.
Thus, The quadrilateral ABCD is not a parallelogram
For question 19:
Given that vertices of a quadrilateral are A(-2,3), B(3,2), C(2,-1) and D(-3,0)
The slope of a line is given m=
Now,
The slope of a line AB:
m=
m=
m=
The slope of a line BC:
m=
m=
m=
m=3
The slope of a line CD:
m=
m=
m=
The slope of a line DA:
m=
m=
m=3
The slope of the line AB and CD are the same
The slope of the line BC and DA are the same
Thus, The quadrilateral ABCD is a parallelogram