Use the 3-4-5 Rule to Square a Perfect Corner. Timothy Dahl April 9, 2015 Comments. Timothy Dahl. Read Full Bio. For construction purposes, in lieu of a framing square tool to make a ...

For a right angle triangle it is: The 3-4-5 triangle is a great way to make sure the corners are square and the panels at a 90-degree angle (see Figure 1, top). If one side of a triangle measures 3 ...