It intersects its midline at ( − 1 2 π , 3.3 ) (− 2 1 ​ π,3.3)left parenthesis, minus, start fraction, 1, divided by, 2, end fraction, pi, comma, 3, point, 3, right parenthesis and it has a maximum point at ( − 2 π , 9.8 ) (−2π,9.8)left parenthesis, minus, 2, pi, comma, 9, point, 8, right parenthesis. What is the period of the function? Give an exact value.