The need for finding of various elements including the areas of a triangle, appeared for many centuries BC at erudite astronomers of Ancient Greece. The area of a triangle can be calculated in various ways, using different formulas. The way of calculation depends on what elements of a triangle are known.

The triangle is the simplest polygon having three tops and three parties. The triangle, one of corners of which is to straight lines, is called rectangular. For rectangular triangles all formulas for triangles of a general view are applicable. However they can be altered, considering properties of a right angle.

If you had a need for any purposes to measure perimeter or some other geometrical size, it is not obligatory for you to be the expert in geometry at all. There is a number of ways to cope with measurement of such sizes, without resorting to various difficult calculations and calculations. However, calculations with use of necessary formulas will be much more precisely. Therefore if you need the maximum accuracy of measurement, find suitable formulas better, remember as to use them and start measurements. If some errors do not upset you, will use a usual thread, for example.

In tasks in geometry often it is required to count the area of a flat figure. In tasks on stereometry usually calculate the area of sides. It is quite often necessary to find the area of a figure and in life, for example, when calculating amount of necessary building materials. For determination of the area of the simplest figures there are special formulas. However, if the figure has irregular shape, then to count its area sometimes happens not so simply.