Takes the secant of a number (usually, an angle).

sec(*angle*)

**Menu Location**

- Press 2nd MATH to enter the MATH popup menu.
- Press A to enter the Trig submenu.
- Press 5 to select sec(.

This command requires a calculator with AMS version 2.07 or higher (it will also work on any TI-89 Titanium or Voyage 200 calculator)

1 byte

The `sec()` command returns the secant (the reciprocal of the 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.

The `sec()` command, along with 11 other trig and hyperbolic functions, was added with AMS version 2.07. It can be easily replaced on earlier versions with 1/cos(x), which is what it simplifies to anyway.

For many common angles, `sec()` 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, `sec()` can be used with complex numbers as well.

```
:sec(60°)
2
:sec(x)
1/cos(x)
:sec(π/2)
undef
```

If `sec()` is applied to a list, it will take the secant of every element in the list. However, it can't be applied to matrices the way `cos()` can (this is probably an oversight; all the trig and hyperbolic functions that were present in all AMS versions work with matrices, but the ones added in version 2.07 do not).

# Error Conditions

**260 - Domain error** happens when taking sec() of a complex number in degree or gradian mode.