ArcCos (ACos)

This function is available only in the Formula Toolbox.

ArcCos expresses the Cosine function in radians between 0 and pi. For example, the ArcCos of 1 equals 0, the ArcCos of 0 = pi/2 and the ArcCos –1 = pi.

The cosine function takes the selected chart value, converts it into radians and calculates a cosine value. For example, the cosine value of 1090 is .99.

This value is calculated as follows:

1090/(2*pi) = 173.478                        Calculates the laps around the unit circle

.478 * (2*pi) = 3.00894                       Takes the leftover lap and converts it to radians

Cos(3.00894) radians = -.991214531     Calculates the Cosine for the corresponding radians

Therefore,

ArcCos(-.991214531) = 3.00894 radians

Example: ACos(@)