Note:

**arccos**refers to "**arc cosine**", or the radian measure of the**arc**on a circle corresponding to a given value of**cosine**. Technical note: Since none of the six trig functions sine,**cosine**, tangent, cosecant, secant, and cotangent are one-to-one, their inverses are not functions.Just so, is Cos 1 the same as 1 cos?

Secant, cosecant and cotangent, almost always written as sec, cosec and cot are trigonometric functions like sin,

**cos**and tan. Note, sec x is not the**same as cos**^{-}**x (sometimes written as arccos x).**^{1}What is the inverse of the cosine?

Specifically, they are the inverses of the sine,

**cosine**, tangent, cotangent, secant, and cosecant functions, and are used to obtain an angle from any of the angle's**trigonometric**ratios.**Inverse trigonometric**functions are widely used in engineering, navigation, physics, and geometry.