Question

1.Given the rotation of triangle ABC shown below, determine the counter-clockwise angle of rotation that occurred about point D. Show all relevant lines and measurements you made to determine your answer.
A) 180°
B) 90°
C) 130°
D) 50°
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Answer 1

Answer:

D. 50º

Step-by-step explanation:

According to the image below attached, blue lines represents line segments $DB$ and $DB'$, the red line creates a right angle regarding $DB$ (90º), where green line creates a flat angle with the same respect (180º). The angle between $DB$ and $DB'$ is less than 90º and 180º, meaning an acute angle. Therefore, the right answer is D.