Answer:
See answers below
Step-by-step explanation:
<u>Problem 1</u>
Recall that  and that
 and that  . Using these two facts, we can rewrite the expression:
. Using these two facts, we can rewrite the expression:

Hence, the first choice is correct
<u>Problem 2</u>
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It's helpful to use the unit circle to solve these kinds of problems. Therefore, the third answer is correct.
<u>Problem 3</u>
Because  and our parameters are
 and our parameters are  , the triangle must be in Quadrant III where
, the triangle must be in Quadrant III where  and
 and  .
.
You may recall the double angle formula  . We can find
. We can find  using
 using  with the Pythagorean Identity
 with the Pythagorean Identity  keeping our parameters in mind:
 keeping our parameters in mind:

Thus,  , which means the third option is correct.
, which means the third option is correct.