Right angle marking out device using Pythagoras theorem employing cord with attached rings at 3:4:5 spacing ratio

摘要

The right angle marking out device uses a cord (1) of a non-expandible material to which rings (2) are attached at points spaced by a ratio of 3:4:5, allowing the cord to be used for marking out a right angle triangle using the Pythagoras theorem. The cord can be wound onto a reel for providing a compact device which can be carried in a pocket.