Step 1: Observe the segment \(PQ\).
Both \(P\) and \(Q\) have \(x\)-coordinate \(0\), so the segment \(PQ\) lies on the vertical line \(x=0\). Step 2: Conclude for any point on the segment.
Any point \(R(a,b)\) on this segment must satisfy \(a=0\) and \(0\le b\le 2\).