There is only one download file today:
http://interactiveds.com.au/software/IP2.ZIP

, but it contains a wealth of different functions dealing with 2D and 3D geometry, including intersections of lines, circles and spheres, simple interpolation functions, and functions for rotating points in 2D and 3D.

The original spreadsheet is described at: Intersections, interpolations, and rotations with updates at IP.xls updated and Another update to IP.xls.

Version 2 included: Finding Circle Centres in 3D , with later updates including:

• Maximum distance between two points
• Interpolation Update
• 3D Intersections
• More 3D Intersections and 3D plotting function
• PView Function

Intersection points of two polylines

Perpendicular distance from points to a polyline

ArcCen Function

PView: Perspective projection of 3D Lines, showing IPPlanePlane output

Output of PView function