Step-by-step explanation:
The area is

Since the width is

Then, the length will be

The answer is D, the alternate exterior angles theorem.
Alternate, because the two angles are on opposite sides of line t.
Exterior, because both angles are outside of the parallel lines.
Therefore, alternate exterior angles theorem.
1 over 4, 2 over 4, 3 over 4 and 4 over 4
THis will be the coordinates of the point at a turning point on the graph.
Since the second derivative is positive (=1) it will be a minimum value of f(x).