Inequalities in triangles represent three factors. Firstly, if two sides of a triangle are not similar, the angle on the opposite of the longer side is bigger than others. To prove this theory, one can take an example of a scalene triangle where no side is similar, and angle on the opposite to the longer side is the greatest one, and vice-versa. Secondly, the sum of two sides of a triangle is higher than the third one. This theory is very easy to prove; one can do it using any triangle.