RADIANS()

Syntax. RADIANS(angle)

Definition. This function converts degrees into radian measures.

Argument

• angle (required) The angle that you want to convert, in degrees

Background. You can calculate the segment of a circle based on the angle as well as on the circumference and arc. This quotient is called a radian or radiant (see Figure 16-22). Because the angle functions in Excel are based on radians, this function is often used to specify the arguments for angle functions.

The following applies:

Circumference (2πr) / arc (b) = round angle (360°) / angle at center (α)

The measure for the radian is the radiant (rad). The full circumference of a circle is 360° or 2π = 6.28318531 rad. A half-circle is π = 3.14159265 rad.

Figure 16-22. The radian in a full circle.

Example. Sea miles are an interesting application. The circumference of the earth is 360° x 60’ = 21,600 arc minutes or sea miles.

More examples for this function are:

• =RADIANS(1) returns 0.017453293 rad.

• =RADIANS(45) returns 0.785398163 rad.

• =RADIANS(90) returns 1.570796327 rad.

See Also

DEGREES()

Sample Files

Use the SIN_COS worksheet in the Chapter16.xls or Chapter16.xlsx sample file. The sample files are found in the Chapter16 folder. For more information about the sample files, see the section titled Using the Sample Files.