The cosine is used in the branch of geometry. In addition, in this picture, it is the chest of the complement of an arch or an angle, indicates the Royal Spanish Academy (RAE) in its dictionary.
It is vitally important to bear in mind that the person who opposes the cosine relation is the secant, the trigonometric relations are cosine, sine and tangent, and the inverse trigonometric relations are the secant, cotangent and cosecant mentioned above.
Suppose we have a right triangle ABC, with one 90º angle and two 45º angles. Dividing one of the opposite legs at a 45º angle and the hypotenuse, we will obtain the sine and then we can calculate the cosine.
Trigonometry will be applied where it is necessary to obtain precise measurements of something, it is applied in most branches of mathematics and also in other disciplines, such is the case of astronomy to measure the nearest stars, the distances of the points geographical, and in navigation systems involving satellites. The geometry of space also makes use of trigonometry.
Trigonometric is the cosine function, which is the result of the quotient between the adjacent leg and the hypotenuse. Said in formula:
Seen like this, it seems very abstract. Try to think of a circumference, of radius one. Then there is the so-called trigonometric circumference, which, by dividing it into quadrants, allows us to represent the trigonometric relationships of any angle.
One way to obtain the cosine of an angle is to represent it in the goniometric circumference, that is, the circumference of the unit centered at the origin. In this case, the value of the cosine coincides with the abscissa of the point of intersection of the angle with the circumference. This construction is what allows us to obtain the cosine value for non-acute angles.
