Acute Angles

🏆Practice types of angles (right, acute, obtuse, flat)

Definition of an acute angle

An acute angle is an angle that measures less than 90° 90° .

Acute angles can appear in triangles, parallelograms, and other geometric shapes where there is an angle less than 90° 90° degrees.

Acute angle

A1- acute angle

Which of the 4 angles presented in the figure corresponds to the description of the acute angle?

what is the definitions of 4 angles

The correct answer is B) 40°

Start practice

Test yourself on types of angles (right, acute, obtuse, flat)!


\( ∢\text{ABC} \) equal to 90°.

What angle is it?


Practice more now

If you are interested in learning more about other topics related to angles, you can check out one of the following articles:

  • Angle Notation
  • Sides, Vertices, and Angles
  • Bisector
  • Right Angle
  • Obtuse Angle
  • Straight Angle
  • Adjacent Angles
  • Vertically Opposite Angles
  • Alternate Angles
  • Corresponding Angles
  • Sum of the Angles of a Triangle
  • Sum of the Angles of a Polygon
  • Sum and Difference of Angles

On the Tutorela website, you will find a wide variety of articles about mathematics

Examples and exercises with solutions of acute angles

Exercise #1

True or false?

One of the angles in a rectangle may be an acute angle.

Video Solution

Step-by-Step Solution

One of the properties of a rectangle is that all its angles are right angles.

Therefore, it is not possible for an angle to be acute, that is, less than 90 degrees.



Exercise #2

True or false?

The sum of two acute angles can be greater than 180 degrees?

Video Solution



Exercise #3

Does the drawing show an adjacent angle?

Video Solution


Not true

Exercise #4

Does the drawing show an adjacent angle?

Video Solution


Not true

Exercise #5

Choose the appropriate triangle according to the following:

Angle B equals 90 degrees.

Video Solution



Review Questions

What is an angle?

An angle is the opening that occurs between two lines that join from a vertex. Angles can be measured in degrees or radians.

What is the classification of angles according to their measure?

Angles are classified into 6 types according to their measure:

  • Acute angle
  • Right angle
  • Obtuse angle
  • Straight angle
  • Reflex angle
  • Perigon angle or also called complete angle

What is an acute angle?

The acute angle is the narrowest angle of all according to its measure. In this case, an acute angle is one that measures less than 90o 90^o

Which of the following angles has a measure less than 90o 90^o degrees?

A) Angle of 200o 200^o

B) Angle of 160o 160^o

C) Angle of 30o 30^o

Answer: In this case, option C is the angle that corresponds to an angle less than 90o 90^o , that is, it is an acute angle.

Join Over 30,000 Students Excelling in Math!
Endless Practice, Expert Guidance - Elevate Your Math Skills Today
Test your knowledge
Start practice