Answer:
The correct system of inequalities is b.
Answer:
a=1, b=2, c=5, d=1, e=6
Step-by-step explanation:

So 
Yes, you are right, if it approaches from the left, the limit is infinity and if it approaches from the right, the limit is negative infinity. The limit does not exist because it reaches infinity as x approaches pi/2 and the limits are the same when the value is approached from the opposite directions.
N > 1/3
n = 1/4
sorry if I was wrong