Let's start with a definition of what the angle.Firstly, it is a geometric shape.Secondly, it is formed by two beams, which are called sides of the angle.Third, the last out of a single point, which is called the vertex angle.Based on these characteristics, we can make a determination: the corner - a geometric shape, which consists of two beams (sides), emanating from one point (vertex).

They are classified according to degree value based on the arrangement with respect to each other and relative to the circumference.Let's start with the corners of species according to their size.

There are several varieties.Let us consider each type.

main types of angles only four - straight, blunt, sharp and straight angle.

** Direct **

He looks like:

His degree is always a measure of 90 degrees, in other words, the right angle - the angle of 90 degrees.But they have such quadrangles as square and rectangle.

** Dumb **

It has the form of:

degree measure of the obtuse angle is always greater than 90 degrees but less than 180 degrees.It can occur in quadrangles such as diamond, arbitrary parallelogram into polygons.

** Acute **

He looks like:

degree measure of an acute angle is always less than 90 degrees.It occurs in all quadrangles but square and an arbitrary parallelogram.

** Extended **

Extended angle has the form:

a polygon does not occur, but it is no less important than the others.Extended corner - a geometric shape, degree measure is always equal to 180º.It is possible to construct the adjacent corners of its top conducting one or more beams in any direction.

There are a few minor types of angles.They are not taught in schools, but at least know of their existence is necessary.Minor species only five angles:

** 1. Zero **

He looks like:

name itself is already talking about the angle of its value.Its interior equals 0 °, and the sides lie on each other as shown in the figure.

** 2. Oblique **

skew can be both direct and blunt and sharp and straight angle.Its main condition - it should not be equal to 0 °, 90 °, 180 °, 270o.

** 3. Convex **

convexity are zero, direct, blunt, sharp and detailed corners.As you know, degree measure of a convex angle - from 0 to 180 degrees.

** 4. Nonconvex **

Nonconvex are angles with a measure of the degree of 181o to 359o inclusive.

** 5. Full **

Full degree angle with a measure of 360 °.

This all types of angles according to their size.Now consider their views on an arrangement plane in relation to each other.

** 1. Additional **

are two acute angle to form a straight line, ie,their sum is 90 °.

** 2. Related **

adjacent angles formed if unfolded through, more precisely, through its vertex, hold the beam in any direction.Their sum is equal to 180 degrees.

** 3. Vertical **

Vertical angles formed at the intersection of two lines.Their measures are equal degree.

now turn to the kinds of angles, positioned relative to the circle.There are only two: the central and inscribed.

** 1. Central **

centerpiece is the angle at the center of the circle.His degree is a measure of degree at least the arc strapped parties.

** 2. Inscribed **

Inscribed is the angle whose vertex lies on the circle, and the sides of which it is crossed.His degree is half the measure of the arc on which it relies.

It's everything about angles.Now you know that in addition to the most famous - sharp, blunt, direct and deployed - in geometry, there are many others of their species.