# TI-BASIC:Cos

**Command Summary**

Returns the cosine of a real number.

**Command Syntax**

cos(*angle*)

**Menu Location**

Press [COS]

TI-83/84/+/SE

1 byte

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/3^r) .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.