The 3-4-5 method of establishing a right angle; use a carpenter's level to insure the line is directly above the nail; and obtaining a diagonal measurement to be sure the plot is square.

Now make sure corner C (angle FCD) forms a 90-degree angle. This is best accomplished by using the 3-4-5 triangle ratio (referring to lengths of the sides of a right-angled triangle whether in inches, feet, meters, etc.). The beauty of this procedure is that it enables you to square up the entire plot using one corner set at 90 degrees. Refer to Table 1 to determine the best ratio to use for your plot.

In our example in Figure 1, the plot is of sufficient size to justify use of the 24-32-40 ratio. A 90-degree angle is established at corner C by first measuring 24 feet from point C and placing a nail directly under the string (point G).

Next, two measuring tapes are attached to the nails at points C and G. A nail is placed at the union (point H) where the 32-foot and 40-foot marks of the respective tapes converge.

After removing the measuring tapes, a line is strung between points C and F. To insure the string is straight, it should be taut, but not so taut as to move the nails. The string should be positioned directly above the nail at point H. If not, the nail at point F is adjusted accordingly. Corner C (angle FCD) should now be approximately 90 degrees.

The distance between points F and E should be the same as the distance between points C and D. If not, the nail at point E (not F) is adjusted accordingly. Corner D (angle EDC) should now approximate 90 degrees.

1. Only adjust the location of points E and F.
2. Move the nails in only one direction along line EF, never towards or away from C or D.
3. When making an adjustment, always move nails in the same direction and at an equal distance.

For example, if line CE is found to be 4 inches longer than line DF, move both nails 2 inches to the left along line EF. Measure lines CF, DE and EF to make sure they are still the proper lengths. Next, measure CE and DF again. Repeat procedure until plot is square.