餘弦 angolul

cosine [cosines]▼(trigonometric function)
noun
[UK: ˈkəʊ.saɪn] [US: ˈkoʊ.saɪn]

arccosine▼(inverse of the cosine function)
noun
[UK: ˈɑːkəʊsˌaɪn] [US: ˈɑːrkoʊsˌaɪn]