`cos(θ)` returns the cosine of θ, which is defined as the x-value of the point of intersection of the unit circle and a line containing the origin that makes an angle θ with the positive x-axis

The value returned depends on whether the calculator is in `Radian` or `Degree` mode. A full rotation around a circle is 2π radians, which is equal to 360°. The conversion from radians to degrees is angle*180/π and from degrees to radians is angle*π/180. The `cos(` command also works on a list of real numbers.

In radians:

```
cos(π/3)
.5
```

In degrees:

```
cos(60)
.5
```

# Advanced Uses

You can bypass the mode setting by using the `°` (degree) and ` ^{r}` (radian) symbols. These next two commands will return the same values no matter if your calculator is in degrees or radians:

```
cos(60°)
.5
```

```
cos(π/3ֿ¹ )
.5
```

# Error Conditions

**ERR:DATA TYPE**is thrown if you supply a matrix or a complex argument.**ERR:ARGUMENT**is thrown if you use more than one number.**ERR:DOMAIN**is thrown if you supply an input ≥1E12.

# Related Commands

# See Also

.