Triangles have three sides and three vertexes. The sum of the interior angles of any triangle is always 180 degrees. Triangles can be classified based on side length as either equilateral, isosceles, or scalene triangles, or based on angle measure as either right, obtuse, or acute triangles.

1. triangles

2. GENERAL FEATURES
The triangle is a three-sided
polygon and therefore it has
three vertexes.
The sum of all the angles
of a triangle is equal to 180º.

3. TRIANGLE CLASSIFICATION

4. According to the meassure of
their sides, triangles can be:
• Equilateral triangle: they have
equal sides and angles.
• Isosceles triangle: they have at
least two equal angles.
• Scalene triangle: they have
three different sides.

5. According to the meassure of
their angles, triangles can be:
• Right triangle: they have a right
angle, that is to say, 90º angle.
Oppsite the right angle is the
hypotenuse and the other two
sides are the legs.
• Obtuse triangle: they have an
obtuse angle (+90º)
• Acute triangle: they have an
acute angle (-90º)