Solutions for the challenges are given here.
Procedure D.1. Procedure D.1. Drawing the Spiral
Turn on Grid and enable snapping to Grid.
Create a three-turn spiral with with the Spiral Tool, placing the Outer handle directly right of the Inner handle.
Draw a rectangle that passes through the Inner handle and encloses the right half of the spiral.
Use rectangle to divide spiral (Path → Division (Ctrl-/)).