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目录

JavaScript Math.cos()

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Examples

let x = Math.cos(3.14);
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Math.cos(0);
Math.cos(Math.PI);
Math.cos(2 * Math.PI);
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Math.cos(x) expects x radians.

To use degrees, convert the degrees to radians.

Math.cos(degree * Math.PI / 180);
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Description

The Math.cos() method returns the cosine of a number.

The Math.cos() method returns a number between -1 and 1.

The Math.cos() method expects the number in radians.

What is Radians?

Radians is an angle's α amount of rotation b on a circle:

Radian
Degrees PI Radians
0° 0 0
1° PI/180 0.0175
30° PI/6 0.52
45° PI/4 0.79
90° PI/2 1.57
180° PI 3.14
360° PI*2 6.28

JavaScript Sine and Cosine Methods:

The Math.sin() Method
The Math.sinh() Method
The Math.asin() Method
The Math.asinh() Method

The Math.cos() Method
The Math.cosh() Method
The Math.acos() Method
The Math.acosh() Method

Syntax

Math.cos( x)

Parameter

Parameter Description
x Required.
A number representing radians.

Return Value

Type Description
Number -1 to 1 The cosine of the number.
NaN if the parameter is not numeric.

The Pythagoran Therorem

Math.sin(), Math.cos(), and Math.tan() are related to the Pythagorean theorem:

Pythagoras

Theorem: c2 = a2 + b2

The sine Math.sin() to the angle is a / c.

The cosine Math.cos() to the angle is b / c.

The tangent Math.tan() to the angle is a / b.

Related Pages:

JavaScript Math

JavaScript Numbers

JavaScript Number Reference

Browser Support

Math.cos() is an ECMAScript1 (ES1) feature.

ES1 (JavaScript 1997) is fully supported in all browsers:

Chrome Edge Firefox Safari Opera IE
Yes Yes Yes Yes Yes Yes

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