Answer:
See explanation
Step-by-step explanation:
The range of the cosine function is 
Therefore
is not defined.
Assuming your question is rather 
Then
in the second quadrant.


If it’s addition, 6+9=15 in multiplication, 6x9=54.
Answer:
a 0 = x + -x
Step-by-step explanation:
variables can be added just like numbers. a number and it's opposite sum to zero.
therefore, x and it's opposite (-x) sum to zero