cosine

(

cosine function

),

trigonometric function

One kind.

Cosine (cosine function), a kind of trigonometric function. At Rt△ABC (

right triangle

), ∠ c = 90 (as shown in the figure), and the cosine of ∠A is that its adjacent side is a triangle.

hypotenuse

, that is, cosA=b/c, or cosa=AC/AB. Cosine function: f(x)=cosx(x∈R).

Extended data:

Isometric trigonometric function

Basic relationship

style

Correlation: tanα

cotα= 1、sinα

cscα= 1、cosα

secα= 1；

Relationship between businesses:

sinα/cosα=tanα=secα/cscα、cosα/sinα= cotα= CSCα/secα；

And the relationship: sin2α+cos2α= 1, 1+tan2α=sec2α,1+cot2α = csc2α;

Square relation: sin? α+cos？ α= 1。