Java Script Math.sin Method
By Stephen Bucaro
Sine 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 hypotenuse.
sine A = opposite/hypotenuse
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 opposite the angle, you can
use the sine of the angle to calculate the length of the hypotenuse.
length of hypotenuse = length of opposite/sine of angle
Example
angle = 40 degrees
opposite side = 9
Java Script Using Math.sin Method
<script type="text/javascript">
var angle = 40;
var opposite = 9;
var hypotenuse = opposite/Math.sin(40 * Math.PI/180);
alert(hypotenuse.toFixed(3));
</script>
The code shown above uses the Java Script Math.sin method. The Math.sin 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: • Rounding a Number with JavaScript • Java Script Trigonometric Methods • JavaScript to Concatenate Strings • The continue Statement • JavaScript .big and .small to Change Text Size • Window Object Properties and Methods • Generating Random Numbers • JavaScript Math Object • The Document Object Model (DOM) • Java Script Events
