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title??? Definition&Description**
 * [[image:snowman_inside_cristalball.gif]]

Basic trigonometric functions (sine, cosine, and tangent)

Basic Trigonometric Functions sine, cosine and tangent (or better known as sin, cos and tan) are a set of ratios between two quantities, in trigonometry, those quantities are the lengths of the sides of a right triangle (sometimes another type of triangle), which are known as hypotenuse, adjacent leg and opposite leg. First of all, sine is the ratio between the opposite leg and the hypotenuse; second, cosine is the ratio between the adjacent leg and the hypotenuse and finally, tangent is result from the division between opposite leg and the adjacent leg. Sin, cos and tan can be represented into a unit circle forming a right triangle, and so, they can be plotted as functions that depends of an angle, but not all the time this trigonometric functions have a graphic sense, we will never see a sin, cos or tan drawn in a triangle because they are just quantities or ratios that are very useful in a lot of fields.



**Classification**

If we imagine a right triangle in the Cartesian plane (with the hypotenuse across the origin) and if we consider the acute angle that it forms with the axis X, as is showed in the next pictures:
 * [[image:58ee1af0.gif caption="58ee1af0.gif"]] ||
 * 58ee1af0.gif ||


 * [[image:575fae10.gif caption="575fae10.gif"]] ||
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then we can classify the sine, cosine and tangent according to the quadrant in which they are, this is, they can be positive or negative, this information is the next chart:
 * [[image:Dibujo.JPG caption="Dibujo.JPG"]] ||
 * Dibujo.JPG ||


 * Comparisons & Contrast**

 In the applications, there are not big diferences between sin,  cos and tan, the importance of each one of them depends on what   is wanted to be calculated, for example:


 * [[image:Aplicacion_de_las_f.g.JPG width="422" height="269" caption="Aplicacion_de_las_f.g.JPG"]] ||
 * Aplicacion_de_las_f.g.JPG ||

Those persons (in the picture) can find the distance between them and the basis of the building or between them and the climb of that building, just knowing the indicated angle and some extra data, (adjacent or opposite leg, hypotenuse) depending of what the want to find.

In the other hand, we can use this functions to obtain some important informations, for example, the distance from the Earth to the Moon:



 However, there is a big similarity,    they are very importants mathematical tools that scientifics, engineers and architects can use to obtain some vital data to do a project, but not only are usefull to people with mathematical experience but for anyone that know some basic trigonometry.

Basic trignometric functions are of vital importance in a lot of fields, like astronomy,  geography (the use of global positioning systems) physics, etc. Therefore,  one can only speak of the great similarity between them: they are very indispensable in the constant progress of the modern world.