SQL ACOS: Calculate Arc Cosine of a Numeric Expression

The SQL ACOS function calculates the arc cosine of a numeric expression that evaluates a float value between -1 and 1.

In math, the arccosine(x) is defined as the inverse cosine(x) when -1≤x≤1.

Syntax

The following shows the syntax of the ACOS function.

ACOS(numeric_expression)Code language: SQL (Structured Query Language) (sql)

Argument

The ACOS function accepts a numeric_expression that evaluates to a float value in the range -1 and 1.

Return Type

The ACOS function returns a floating-point number in radians.

Examples

The following example returns the arc cosine of 0.5

SELECT ACOS(0.5);Code language: SQL (Structured Query Language) (sql)

      acos
-----------------
 1.0471975511966
(1 row)Code language: SQL (Structured Query Language) (sql)

To see the degrees value, you use the DEGREES function.

SELECT DEGREES(ACOS(0.5));Code language: SQL (Structured Query Language) (sql)

 degrees
---------
      60
(1 row)
Code language: SQL (Structured Query Language) (sql)

Most database systems support the ACOS function with the same behavior.