Gives the area of any triangle from its three side lengths. No height, no angles, and no dropping a perpendicular to find one.
By Sumarth Mehta. Original release page
How to install it
- Download the program with the button above. You'll get a .tns file, the file type TI-Nspire calculators use.
- Open nspireconnect.ti.com in Chrome on a computer or Chromebook, and plug your calculator in with its charging cable.
- Choose File Transfer, then To Calculator, then From Computer, and pick the .tns file you just downloaded.
- When it lands, the calculator shows a prompt. Choose Open to jump straight into it.
It sits in My Documents afterwards, so you can reopen it any time.
TI's web app only supports the CX II and CX II CAS. If you have an original CX, or you already use the TI-Nspire Student Software, sending the file through that works the same.
Running it
Open the document and go to its calculator page. There are two commands and they take the same three arguments, the side lengths in any order:
- herons_formula(side1, side2, side3) gives you the area.
- herons_steps(side1, side2, side3) gives you the area and the working that leads to it.
Which one to use
It depends on whether the marks are for the number or for the method. herons_steps lays out the semi-perimeter and the product under the root on the way to the answer, which is what a "show your working" question wants. herons_formula is the one to use when you just need the area to plug into something else.
Exact and decimal, both
Heron's formula almost always lands on an irrational number, and a triangle area of 6√6 is not the same answer as 14.6969. You get the simplified radical and the decimal together, so whichever form the question asks for is already on screen.