Which of the following correctly represents ArcCos?

The term ArcCos refers specifically to the inverse function of cosine, which is mathematically denoted as cos^(-1)(x). This notation indicates that it is the function which, when applied to the cosine of an angle, returns the angle itself. Thus, if you take the cosine of an angle and then apply ArcCos (or cos^(-1)), you retrieve the original angle.

The notation "cos^(-1)" is commonly used to avoid confusion with other notations that can resemble powers. In many contexts, including scientific and engineering, it is understood that cos^(-1)(x) refers to the angle whose cosine is x, making it a clear representation of the inverse cosine function.

Other answers might represent concepts related to trigonometric functions but do not specifically define ArcCos correctly. For example, while "Cos" simply refers to the cosine function itself, "ArcCosine" could be a more verbose way to describe the concept, but does not reflect the conventional notation. Similarly, "Inverse Cos" is somewhat ambiguous and not a standard way to denote the function in mathematical contexts. Thus, the use of cos^(-1) is the most precise and universally recognized representation of ArcCos.