Angle 1 and angle 4 are alternate angles
Angle 2 and angle 3 are alternate angles
Angle 1 and angle 2 are complementary angles
Angle 3 and angle 4 are complementary
How the relationship between the angles are determined
In a parallelogram, the postulate of opposite sides being congruent states that opposite sides are equal in length and parallel.
From the the figure
The longer sides area parallel (given)
The Shorter sides are parallel and congruent (opposite sides congruent postulate)
Therefore the flag is parallelogram
The yellow ribbon is diagonal and it is a transversal.
Angle 1 and angle 4 are alternate angles
Angle 2 and angle 3 are alternate angles
The angles at the corner of a rectangle is 90⁰. They are complementary.
Angle 1 and angle 2 are complementary angles
Angle 3 and angle 4 are complementary