If the arms of one angle are respectively parallel to the arms of anot...
Explanation:Let's consider two angles, say angle A and angle B, whose arms are respectively parallel to the arms of another angle, say angle C.
Case 1: The arms of angles A and C are parallel to the arms of angle B
In this case, we can say that angle A and angle B are alternate interior angles. According to the alternate interior angles theorem, alternate interior angles formed by a transversal and two parallel lines are equal. Therefore, angle A and angle B are equal.
Also, since angle A and angle B are adjacent angles (they share a common vertex and a common arm), the sum of these angles is equal to the measure of angle C. Therefore, angle A and angle B are supplementary to each other.
So, in this case, we can say that the two angles are both equal and supplementary.
Case 2: The arms of angles A and B are parallel to the arms of angle C
In this case, we can say that angle C and angle B are corresponding angles. According to the corresponding angles theorem, corresponding angles formed by a transversal and two parallel lines are equal. Therefore, angle C and angle B are equal.
Also, since angle A and angle B are adjacent angles (they share a common vertex and a common arm), the sum of these angles is equal to the measure of angle C. Therefore, angle A and angle B are supplementary to each other.
So, in this case, we can say that the two angles are both equal and supplementary.
Conclusion
Thus, we can conclude that if the arms of one angle are respectively parallel to the arms of another angle, then the two angles are either equal or supplementary.
Therefore, the correct answer is option D - Either equal or supplementary.