The triangle is made by three parties which total length is called perimeter. The closed broken line formed by the parties of this figure is called perimeter too. It limits the site of a surface of a certain square. Lengths of the parties, perimeter, the area and also corners in tops - all this is connected among themselves by certain ratios. Use of these ratios will allow to calculate missing parameters of a figure, for example, its perimeter and the area.

Equilateral call the triangle having three equal parties and three identical corners. Such triangle is called still correct. Height which is carried out from top to the basis at the same time is a bisector and a median what follows from that this line divides a top corner into two equal corners, and the basis by which falls, into two equal pieces. These properties of a triangle will help to calculate its square equal to a half of the work of height at any of its parties.

If it is necessary to find the area of the most usual triangle set by straight lines it automatically means that the equations of these straight lines are set too. The answer will also be based on it.

To be able find the area of a figure can be it is useful also after leaving school. For example, this knowledge is useful if you do repair, and want to know how many it will be required paints for a surface of any form. Or suddenly you wanted to create a flower bed and to calculate amount of the necessary materials, it is necessary to determine its area.