Answer:
Part 2) Triangle ABC is a right triangle (see the explanation)
Part 3) Quadrilateral QRST is not a parallelogram (see the explanation)
Step-by-step explanation:
Part 2) we have
A (5, 2), B (2, 4), and C (7, 5)
Plot the figure to better understand the problem
see the attached figure
we know that
the formula to calculate the distance between two points is equal to
step 1
Find the length side AB
A (5, 2), B (2, 4)
substitute the values in the formula
step 2
Find the length side BC
B (2, 4), C (7, 5)
substitute the values in the formula
step 3
Find the length side AC
A (5, 2), C (7, 5)
substitute the values in the formula
step 4
Verify if the triangle ABC is a right triangle
we know that a right triangle must satisfy the Pythagorean Theorem
so
Remember that the hypotenuse is the greater side
substitute the values
----> is true
therefore
Triangle ABC is a right triangle
Part 3) we have
Q (5, 1), R (8, 7), S (14, 10) and T (10, 2)
we know that
The opposite sides of a parallelogram are parallel and congruent
the formula to calculate the distance between two points is equal to
Step 1
Find the length side QR
Q (5, 1), R (8, 7)
substitute in the formula
Step 2
Find the length side RS
R (8, 7), S (14, 10)
substitute in the formula
Step 3
Find the length side ST
S (14, 10), T (10, 2)
substitute in the formula
Step 4
Find the length side QT
Q (5, 1), T (10, 2)
substitute in the formula
Step 5
Compare the length of the opposite sides
QR and ST
RS and QT
Opposite sides are not congruent
therefore
Quadrilateral QRST is not a parallelogram