The answer to that is -50. Hope this help
The required value is the angle theta and the value of the cosine of the angle is 0.9659
Given the expression of sine of an angle expressed as;

For us to get the cosine of the angle, we need to get the value of theta first as shown:

Next is to get the value of cos theta

The required value is the angle theta and the value of the cosine of the angle is 0.9659
Learn more here: brainly.com/question/13729598
Opposite angles are equal so the equation is
x + 71 = 108 (A)
I can't see the page, however if you need help with the whole thing, we could possibly message each other on here OR if you are comfortable, we could email.
I don't know what math you're in though because I can't see the page but I'm sure I can help you. I'm in calculus.
Best wishes!