|x||The angle (in degrees) to return the inverse cosine of.|
Returns the inverse cosine of x, in that if dcos(val)=n,
darccos(n)=val, and the resulting number will be between 180 and
NOTE: This will only accept a number between -1 and 1 (anything else will throw an error).
val = arccos(-1);
This will set "val" to 180.