The first thing we are going to do before entering fully into the establishment of the meaning of the term acute angle is to know the etymological origin of the two words that give it its shape:

-Angle, in the first place, derives from the Greek. Specifically, it emanates from “ankulos”, which can be translated as “bent” and which later became Latin as “angulus”, where it already takes the meaning of “angle”.

-Acute, on the other hand, has its origin in Latin, exactly in the word “acutus”, which is synonymous with “acute”. That in turn comes from the verb “acuere”, which is synonymous with “sharpen”.

Two rays that share the same vertex as point of origin form a **angle**. According to the characteristics that are analyzed, it is possible to differentiate between multiple types of angles.

A **acute angle** is an angle that **measures more than 0º and less than 90º**. This means that if we only consider the **integer numbers**, an acute angle measures between 1º and 89º.

This definition of the measures of the acute angles allows us to affirm that they are angles greater than the **null angles** (whose measure is equal to 0º) but less than the **right angles** (90º), the **obtuse angles** (more than 90º and less than 180º), the **plain angles** (180º) and the **perigonal angles** (360º).

Continuing with the **classifications** of the acute angles, we can highlight that they belong to the set of **convex angles**, which covers all angles with measurements greater than 0º and less than 180º, unlike the **concave angles** (which measure more than 180º and less than 360º).

It is possible to find acute angles in different geometric figures. In the **right triangles**, two acute angles and one right angle appear. The **obtuse triangles**, for their part, they have two acute angles and one obtuse angle. In the case of **acute triangles**, the three interior angles in the figure are acute angles.

We can also notice sharp angles in objects or elements of everyday life. The most common way to cut the **Pizza** It is in triangular portions: in each portion we can find three acute angles.

In addition to all the above, we can indicate that in order to measure an acute angle it is necessary to resort to the use of a protractor. This article can be in two fundamental ways: with a semicircular shape, to be able to measure angles of a maximum of 180º, or with a circular shape. The latter is used to measure approximately any type of angle, since its maximum is at 400º.

In the same way, we cannot ignore the fact that certain mathematical and trigonometric operations can be performed with the acute angles in triangles. Thus, for example, the sine can be calculated, which will be the result of the quotient between the length of the leg opposite the angle and the hypotenuse.

And this without forgetting that, in addition, you can proceed to calculate the cosine, the tangent, the secant, the cosecant and the cotangent.