# The concept of a triangle.

geometry - very entertaining science.It not only develops logical thinking, but also helps improve attention and memory.This is one of the basic sciences which is taught in schools and other educational institutions.Properties of geometric figures given it special attention.Consider the properties of an isosceles triangle and its very concept.

triangle is the three points, connected lines, and do not lie on a straight line.It has three sides.Two of them called the sides, and the third - base.

This geometric shape is different.If the triangle has all the rough edges, it is called acute-angled.

In the case where one of the available angles obtuse triangle called obtuse.

If one of the angles of geometric figure is equal to 90 °, ie, the line is called a rectangular triangle.In any case, the sum of its three angles equal to 180 °.

In a right triangle the side that lies opposite the right angle is called the hypotenuse.The remaining two sides are called legs.

Due to these features, there are propertie

s that are inherent in this figure.Thus, if the elements of one triangle (sides and angles) are the same elements of the other triangle, these geometric figures are equal.This statement is a theorem that has proof.

Another theorems concerning the properties of this figure, says that if any two sides of a triangle and the angle located between them, are these elements of another triangle, then the figures themselves are equal.The same statement applies to the case when the triangle is equal to side and two angles that are adjacent to it.Another theorem states that if a triangle is equal to all the parties, these figures, respectively, are also equal.

There is the notion of an isosceles triangle.It is a triangle in which two sides are equal.The two sides having the same length, are called lateral.The third party is the base of the triangle.

consider the properties of an isosceles triangle.Any segment drawn from the vertices of the triangle to the middle of the opposite side is called the median.

Media isosceles triangle has its own characteristics.In this case, the median drawn to the ground is also a high and bisector.Take the example of an isosceles triangle ABC.It side AB - this ground.From the vertex C to the base held the median CD.A triangle are equal.This follows from the equality of sides AC and BC, as the triangle is isosceles.The angles at the base are equal, which follows from the properties of an isosceles triangle on the equality of the angles at the base.Parties that are the basis of these triangles are equal, as the median of the base triangle ABC divided into two equal parts.

From this it follows that all the angles of a triangle are equal, so the median is also the bisector as divides in half the angle.Bisector - a ray drawn from a corner of the triangle to the opposite side, and divides the angle into two equal parts.The angles formed by the median of the base also are equal and 90 °.In this case, the median - this is the height of an equilateral triangle.Height - is the perpendicular dropped from the corner to the opposite side of the triangle.QED.More

from one property to be an isosceles triangle and that the angles at the base of the figure are also equal.

thus prove two key features of the triangle in which two sides are equal.

prove properties of an isosceles triangle is simple enough.The main thing - to be patient and use logical thinking based on existing knowledge in this area.