Straight, blunt, sharp and unfolded angle

Let's start by determining what an angle is. First, it is a geometric figure. Secondly, it is formed by two rays, which are called the sides of the corner. Thirdly, the latter come out of one point, which is called the vertex of the angle. Proceeding from these signs, we can make a definition: an angle is a geometric figure that consists of two rays (sides) emerging from one point (the vertex).

They are classified by degree, by location relative to each other and relative to the circumference. Let's start with the types of angles by their size.

There are several of them. Let us consider each species in detail.

The main types of angles are only four - a straight, blunt, sharp and unfolded angle.

Straight

It looks like this:

Its degree measure is always 90 degrees, in other words, the right angle is 90 degrees. Only they have such quadrangles as a square and a rectangle.

Stupid

It looks like this:

The degree of the blunt angle is always greater than 90 °, but less than 180 °. It can occur in such quadrangles as a rhombus, an arbitrary parallelogram, in polygons.

Acute

It looks like this:

The measure of the acute angle is always less than 90 °. It occurs in all quadrangles except for a square and an arbitrary parallelogram.

Deployed

The unfolded angle is as follows:

In polygons, it does not occur, but is no less important than all the others. The unfolded corner is a geometric figure, the degree measure of which is always 180 °. On it it is possible to construct adjacent angles, having drawn from its top one or several rays in any directions.

There are several secondary types of corners. They are not studied in schools, but they need to know about their existence. There are only five minor angles:

1. Zero

It looks like this:

The very name of the corner already speaks of its magnitude. Its internal area is 0 ^o , and the sides lie on top of each other as shown in the figure.

2. The oblique

The oblique can be straight, and blunt, and sharp, and unfolded. Its main condition is that it should not equal 0 °, 90 °, 180 °, 270 °.

3. Convex

Convex are zero, straight, blunt, sharp and unfolded angles. As you have already understood, the degree measure of the convex angle is from 0 ° to 180 °.

4. Non-convex

Corners with a degree measure from 181 to 359 inclusive are nonconvex.

5. Full

The angle is full with a degree measure of 360 ^° .

These are all types of angles by their size. Now consider their views on the location in the plane relative to each other.

1. Additional

These are two acute angles forming one straight line, i.e. Their sum is 90 ^о .

2. Related

Adjacent angles are formed if through a developed, more precisely, through its vertex, to hold the beam in any direction. Their sum is 180 ^o .

3. Vertical

Vertical angles are formed when two straight lines intersect. Their degree measures are equal.

Now go to the types of angles, located relative to the circle. There are only two of them: central and inscribed.

1. The Central

The central is the angle with the vertex in the center of the circle. Its degree measure is equal to the degree of a smaller arc, tied together by the sides.

2. Inscribed

Inscribed is the angle whose vertex lies on the circle, and whose sides it intersect. Its degree measure is equal to half the arc, on which it rests.

It's all about corners. Now you know that in addition to the most famous ones - sharp, blunt, direct and unfolded - there are many other kinds of geometry in geometry.