The inverse trigonometric function that finds the angle whose cosine is a given value, also called arccosine.
From anti- (used in mathematics to mean inverse) + cosine (from Latin complementi sinus, the sine of the complement). This mathematical terminology emerged in the 18th century.
Anticosine is one of those quirky math terms where 'anti' doesn't mean 'against' but 'inverse'—if cosine tells you the ratio from an angle, anticosine goes backward to find the angle from the ratio.
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