# What is the cosine?

Dilettantes in mathematics will tell you what iscosine of the angle in the algebraic concept. In algebra, the cosine of the angle (acute) in a right-angled triangle is equal to the ratio of the hypotenuse to the adjacent leg. If you give an example of a formula, then it will look like cos t = a / c. To remember the value of the cosine, you need to know that in almost every pair of numbers the cosines, that is, their values, are always the first.

It is also worth remembering that at the end of any cosine axis (x-axis) they are equal to modulus 1, and if the sines are equal to 1 at the ends of the sine axis (y-axis), then the cosines are 0.

If you go into geometry, you will notice thatThere is no special difference in the concepts (in algebra and geometry the concepts of cosines are very similar), the only difference is that in geometry there is a theorem.

According to the cosine theorem, the side squaretriangle is equated to the sum of the squares of its two other sides, and from this sum the double product of the same sides, multiplied by the cosine of the angle between them, is subtracted. Do not forget that the sides in the triangle are proportional to the sinuses of the opposing corners. It follows from the theorem that the larger side lies against a larger angle. Now you know what the cosine is.