Trigonometry is the study of right triangles, including their sides, angles, and the ratios between them. In right triangles, the length of each side of a triangle to one of the other triangles for a given angle is always in a specific ratio, and those ratios are what Trigonometry is concerned with. With trigonometry, we are given – because someone once discovered – information regarding the relationship between the length of one side to another for any two sides at any angle, and therefore can calculate the missing information regarding the third side or angle. In essence, because we know these ratios – the sine, cosine, and tangent – we can use them to determine unknown measurements of lengths and angles.