15) factor out cos: cos(x)(sin(x)+1)=0
Now this is true when either cos(x)=0 (x=pi/2 and 3pi/2)
Or when sin(x)=-1 (x=3pi/2)
So it's solutions are pi/2 and 3pi/2
Answer:graph B
Step-by-step explanation:because if a line is parallel they have no solutions with a certain slope
If two lines intersect then they must have at least a solution
Answer:
C) 
Step-by-step explanation:
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Therefore, this solution is genuine.
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Answer:

Step-by-step explanation:
we know that the circumference is equal to

we have

substitute

