Arccos (or inverse cosine) is the inverse function of cosine. It returns the angle whose cosine is x. The domain of arccos(x) is [-1, 1], and the range is [0, π] (or 0° to 180°).
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Pro Tips
The input value must be between -1 and 1.
Arccos is always positive (ranges from 0 to 180 degrees).
Arccos(0) = 90 degrees.
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Fun Facts
"In navigation, arccos is used to find the angle of sailing relative to the wind."
"Arc-functions are called 'inverse' because they undo what the original trig function did."
"Cosine and Arccos are only true inverses if we restrict the domain of cosine to [0, π]."
