This series is what dictates the graph above.
The Attempt at a Solution
I don't understand what's going on. If they're using the series that i pasted below then why aren't they multiply each value in the brackets by -2/pi?
I also don't get why terms in the brackets are
[(-2pi + 0) + f(-2pi - 0)]
Where did they come from? Where does 1/2 come from that multiplies the brackets. very confused.