<h3>Answer:</h3>
- left picture (bottom expression): -cot(x)
- right picture (top expression): tan(x)
A graphing calculator can show you a graph of each expression, which you can compare to the offered choices.
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You can make use of the relations ...
... sin(a)+sin(b) = 2sin((a+b)/2)cos((a-b)/2)
... cos(a)+cos(b) = 2cos((a+b)/2)cos((a-b)/2)
... cos(a)-cos(b) = -2sin((a+b)/2)sin((a-b)/2)
Then you have ...
and ...