polar graphing, supposed range is between $0$ to $\pi,$ but graph drawn range from $-\pi/2$ to $\pi/2$

Question

I'm currently studying "area bound by polar curves" on khan academy, and below is one of the question I have encountered

I am puzzled by part $2$ of the official solution. I can't seem to figure out why the graph is drawn between $-\pi/2$ and $\pi/2,$ even though the supposed range is between $0$ and $\pi?$

Could someone please provide some additional explanation/clarification?