The Arccos (cos^-1) command

We're glad you came by, but you might find what you're looking for elsewhere.

TI-Basic Developer is not the site it once was. While its information on commands and other calculator features remains almost second-to-none, its forum, archives, and even hosting service, Wikidot, have been decaying for years. The calculator community would love to see what you're working on, or help you in your next coding adventure, but TI-Basic Developer is no longer the place to do it.

Instead, you should head over to Cemetech (primarily American) or TI-Planet (primarily international). Both are active, well-established forums with their own archives, chatrooms, reference material, and abundant coding tools and resources. We'll see you there, we hope.

arccos.png

Command Summary

Takes the inverse cosine of a number (usually, an integer or fraction).

Command Syntax

cos-1(angle)

Menu Location

Press [2nd] COS button to enter cos-1(.

Calculator Compatibility

This command works on all calculators.

Token Size

1 byte

The cos-1() command returns the inverse cosine of an angle measure. Naturally, the result depends on the angle mode the calculator is in: radian, degree, or (in AMS version 3.10) gradian. You can also use one of the r, °, G marks to specify an angle mode.

For many common angles, cos-1() can compute an exact result. Other angles, the calculator will leave alone unless it's in approximate mode (or unless you make it approximate), and then it will give a decimal approximation. As long as the calculator is in radian mode, cos-1() can be used with complex numbers as well.

:cos⁻¹(1/2)
           π/3
:cos⁻¹(-1/2)
           2π/3
:cos(cos⁻¹(x))
           x

If cos-1() is applied to a list, it will take the inverse cosine of every element in the list.

Advanced Uses

The cos-1() of a matrix is not (in general) the same as taking the cosine of every element of the matrix. I hope that someone more qualified to talk about this updates this part of the page.

Error Conditions

  • Please update this part too

Related Commands

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-Noncommercial 2.5 License.