The code `arcosine(.5)` is likely attempting to calculate the arccosine...

The code arcosine(.5) is likely attempting to calculate the arccosine of 0.5. The arccosine function (often denoted as acos()) is a mathematical function that returns the angle (in radians) whose cosine is the specified value. In this case, the code is trying to find the angle whose cosine is 0.5.