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Java Script Math.tan Method

Tangent is a trigonometric function. Based on a right triangle. It's the ratio of the length of the opposite side to the length of the adjacent side.

Tangent A = opposite/adjacent

Identifying the sides of a right triangle

In identifying the sides of a right triangle, the side next to the angle for which we are using the trigonometric function is called the adjacent side. The side opposite that angle is called the opposite side.

If you know an angle and the length of the side adjacent to the angle, you can use the tangent of the angle to calculate the length of the opposite side.

length of opposite = length of adjacent * tangent of angle

Example

angle = 35 degrees
adjacent side = 10

Java Script Using Math.tan Method

<script type="text/javascript">

var angle = 35;
var adjacent = 10;

var opposite = adjacent * Math.tan(35 * Math.PI/180);

alert(opposite.toFixed(3));

</script>

The code shown above uses the Java Script Math.tan method. The Math.tan method requires the angle passed to it to be in radians. A radian is the angle of an arc created by wrapping the radius of a circle around its circumference. It sounds like a weard unit, by by coincidence there are 2 PI radians in a complete circle. This makes this much easier in fields like calculus. To convert degrees to radians, multiply by PI/180.

The code shown above also uses the Number objects .toFixed(n) method. This method converts a value to a number with n digits to the right of the decimal point.

More Java Script Code:
• A Brief History of JavaScript
• JavaScript .big and .small to Change Text Size
• Rounding a Number with JavaScript
• Extract Part of a String
• Java Script Trigonometric Methods
• Using the Java Script eval() Function
• The while Loop
• Java Script Events
• Java Script Math.sin Method
• The Browsers History Object

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