ReferenceExpressionsTrigonometryArc CosineReturn the arc cosine of a.acos( a )# Return the arc cosine of a. Description# acos( a ) Return the arc cosine of a in radians. Parameters# a Value [-1 to +1] Return value# arc cosine of a Example usage# acos( 1 ) Returns 0. Last updated Sep 2, 2019PreviousSquare rootNextArc Sine