While you may not have believed your high school math teacher when you were told “you will use this later in life”, the triangle is your friend. However you don’t need to know all of the trigonometry your math teacher tried to pound into your head to harness the power of the triangle.
The two things that triangles do for you. They allow you make sure a corner is square and derive a length of something it is hard to directly measure. And while there is some math you can use to figure this out there are some simple ways to do it as well.
For any kind of layout that has four sides with the opposite sides being of equal length you can simply measure the distance of each set of opposite corners and when they are the same then you will know each corner is square. This only works on 4 sided layouts that are supposed to be a square or rectangle.
If you need to create a right angle between two lines you can use the 3-4-5 rule. This involves measuring out 3 on one leg of the 90 degree angle and 4 on the other. By making sure the last side of the triangle it 5 that will ensure the opposite corner is 90 degrees. What makes this great is it doesn’t matter what the units are as long as the ratio is 3-4-5. It can be inches, meters or longer (i.e. 30′-40′-50′). Picking measurements that make up a larger percentage of the size of of what you are trying to layout will give you them most accuracy.
One of the rules of a triangle with angles of 90-45-45 degrees is that the two sides that are connected at 90 degrees are always the same length. Further if you can establish a smaller triangle inside of a larger one to establish the proper angles it extended to the larger triangle. You can use this to estimate the height of something.