arccos

9.9

An angle whose cosine equals a given number

noun
/ˈɑrˌkɔs/

Specialized

: arccos

The value of arccos(0.5) is 60 degrees or π/3 radians.

Examples

To find the angle, take the arccos of the ratio of the adjacent side to the hypotenuse.
Many calculators have a dedicated button for the arccos function.
The arccos function is essential in trigonometry.
To find the angle, use the arccos of the cosine value.
Many calculators have a dedicated button for the arccos function.
The value of arccos(0.5) is 60 degrees or π/3 radians.
To find the angle, take the arccos of the ratio of the adjacent side to the hypotenuse.

Synonyms

inverse cosine

vsarccos

Specialized

8.1

An angle that has a given cosine value

is the same function but commonly represented by a short symbol

arccosine

vsarccos

Specialized

9.9

A function that gives the angle whose cosine equals a given number

is identical in meaning but often written as a concise symbol

arc cosine

vsarccos

Specialized

8.8

To find the angle whose cosine equals a given number

is the same meaning but more often written as one word

Surface Forms

arccos singular

arccos plural

Morphology

arccos = arccosine (semi-transparent) = arc + cosine

Arccos is a straightforward clipped form of 'arccosine', so the relation to the full form is clear.

Etymology

Arccos joins arc, meaning 'curved part of a circle', and cos, short for cosine. So arccos gives the 'arc' or angle that has a given cosine number, which is why it returns the angle whose cosine is that number.