Because the values of circular functions repeat every \( 2 \pi \) , they are used to describe things that repeat periodically. For example, the maximum afternoon temperature in a given city might be modeled by the formula below. In the formula, trepresents the maximum afternoon temperature in month \( x \) , with \( x = 0 \) representing January, \( x \) representing February, and so on.
\( t = 15 - 10 \cos \frac { x \pi } { 6 } \)
The maximum afternoon temperature in January is \( 5 ^ { \circ } \)
(Round to the nearest integer as needed.) In May, the maximum afternoon temperature is \( 20 ^ { \circ } \)
(Round to the nearest integer as needed.)
The maximum afternoon temperature in September is \( \square ^ { \circ } \)
(Round to the nearest integer as needed.)