arccos

The trigonometric arccosine function.

Syntax

For real values, arccos is the inverse of the restriction of the trigonometric cosine function to [0, π]; the domain is [−1, 1].

In general, arccos(z) is defined as

arccos(z) = π/2 + i⋅ln(i⋅z + √(1 − z^2))

where z is a complex number. Notice that the general definition will be used also for real arguments outside of [−1, 1].

arccos(√3/2)

0.523598775598	(=π/6)

arccos(−1/2)

2.09439510239	(=(2/3)⋅π)

arccos(2)

1.31695789692⋅i

arccos(i)

1.57079632679 − 0.88137358702⋅i