Respuesta :
Answer:
D) Vertical Angles
Step-by-step explanation:
This is due to the fact angles 1 and 2 and vertical angles. This is supported by the definition of a vertical angle.
The missing phrase in Terra's proof is vertical angles or opposite angles.
What are opposite angles?
When two lines intersect each other, the angles formed opposite to each other are equal.
The phrase missing in Terra's proof is explained below:
Terra explains how the diagram is a parallelogram.
She says that "For triangles AOB and COD, angle 1 is equal to angle 2. as they are ". It is not explained why these angles are equal.
These angles are equal because they are opposite angles or vertical angles.
When two lines intersect each other, the angles formed opposite to each other are equal.
Therefore, we have found that the missing phrase in Terra's proof is vertical angles or opposite angles.
Learn more about vertical angles here: https://brainly.com/question/1673457
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