ACOS

Syntax: ACOS(X)

X = a numeric value between -1 and 1.

ACOS returns the arc cosine of angle X. The result is the angle (in radians) whose cosine is X and ranges from 0 to $\pi$. To convert the result from radians to degrees, use the DEGREES function.

Examples:

ACOS(1) = 0

ACOS(R3) = 1.670963748, where R3 = -0.1

DEGREES(ACOS(0)) = 90

ACOS(-20) = Error - ACOS, domain is -1 $<$= x $<$= 1

Excel function: ACOS