Sin cos

"Sin" stands for "sinus". The sinus of any angle is defined, in a rectangle triangle, as the ratio of the side opposed to the angle and the hypotenuse. The sinus is useful because it is unique to any angle, which means that the ratio of the opposite side and the hypotenuse in any rectangle triangle is always the same given a certain angle. "Cos" stands for "cosinus". The cosinus of any angle is defined, in a rectangle triangle, as the ratio of the side adjacent to the angle and the hypotenuse. Like the sinus of an angle, the cosinus of an angle will always be constant, which means that, given a certain angle, the ratio will always be the same even if the triangles don't have the same size. Sinus and Cosinus are very useful to determine missing informations in rectangle triangles. In fact, with only two informations (angle and side), you can find every information on this triangle.