Answer:
i can't see your handwriting
Given:
Consider the below figure attached with this question.
To find:
The measure of angle r by using the cosine rule.
Solution:
According to Law of Cosine,

Using the Law of Cosine, we get




On further simplification, we get






Therefore, the measure of angle r is 106.78 degrees.
Reflecting over the y-axis
Just have a very grate day