CLOSURE: Closure Calculator

For Texas TI-84 Plus calculators. Calculates the bearing & distance of a shape’s missing side in degrees, minutes, and seconds. Also supports double-missing-distance.

Free DownloadCLOSURE2 with more features

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This program operates on “whole circle” bearings (otherwise known as azimuths or “true bearings”), which go from 0° to 360°, using degrees, minutes and seconds. These bearings are commonly used throughout the British Commonwealth (UK, Australia, New Zealand, Canada, India, South Africa) as well as Russia, Brazil, Saudi Arabia and United Arab Emirates.

This program is useful in scenarios when:

• You want to find the direct bearing and distance between two points, but you only have indirect measurements (via other points)
• You want to convert a northing & easting (or a chainage & offset) into a bearing and distance
• You want to convert a bearing and distance into a northing & easting (or a chainage & offset)
• You want to find the “double missing distance”

Simple Example

Let’s say you have points A, B and C. You want to find the bearing and distance from A to C.

1. Press STAT, ENTER to access the table editor. You should see L1 and L2 in columns.

   (If the lists do not appear, press STAT, 5, ENTER and then try again.)

2. Place the known bearings in list L1
   (in the form D.MMSS so that 45° 20’ 30” would appear as 45.2030)

3. Place the known distances in list L2

4. Press PRGM and choose CLOSURE to run the program, and press ENTER and perform the calculation.

   

   This gives the bearing and distance, starting at the final point (C in our diagram) and returning to A.

   The second bearing shows the reverse direction – rotated exactly 180°.

   The distance is rounded to 4 decimal places.

   The decimal bearing will be stored in variable B, in case you want to perform further operations on it. The distance will be stored in variable D.

Tips

• Make sure that you follow the sides of the shape in a consistent order (either clockwise or anti-clockwise). If you don’t, you’ll get an incorrect answer!

Video Tutorial

The following video demonstrates CLOSURE2, a more advanced version with extra shortcuts. With this free CLOSURE app, all inputs need to be made via the list editor, and not all features are available.

Working with Feet, Inches & Links

If you want to perform a closure using feet & inches, and have it converted into metres, then you can enter the distance using the letters F and I.

Press the ALPHA button to type letters into your calculator.

For example, to use a distance of 10 feet, 2 inches and have it converted to metres, you would type:

10F+2I

If you would like the result to be in decimal feet, enter:

10+2/12

The app does not currently support showing a result in feet and inches. You will need to convert it manually.

To enter links use the letter L:

120.5L

Double Missing Distance

To calculate a double missing distance:

1. Enter the two additional bearings into list L1 and leave the two distances blank in L2

2. Run CLOSURE to display the result