# Triangles: Knowing the 3 Sided Geometrical Shape ExecutiveChronicles.com | Triangles: Knowing the 3 Sided Geometrical Shape |In geometry a fig with 3 sides is known as a triangle. A triangle is nothing but a 3 sided figure with 3 angles in it. The addition of all 3 angles of a triangle is equal to 180 °. The logic behind the addition of angles of a triangle being 180 ° is the formula of addition of interior angles of a polygon. A polygon is any figure with 3 or more than 3 sides; it should also be a closed figure. So a triangle is also a polygon. Now for polygon the addition of all interior angles is determined by the formula:

Addition= (2*n-4)*90 °, here n = number of sides

The measure of each interior angle of a regular polygon is given by the formula,

Angle= (2*n-4)*90 °/n , here n = number of sides

Regular polygon is a special case of the polygon in which all sides are equal in length. For example equilateral triangle, square etc. In addition to being all the sides equal in length all angles are also equal in length. There is a wide range of application of knowledge of triangles in different topics such as trigonometry, geometry, mensuration etc. There are various types of triangles. Some of which are listed as under:

• Acute triangle: These are the triangles which have all of their angles measuring between 0 ° and 90 °. The thing to be noted here is that the measure should necessarily lie between these two and not beyond them. The addition of all 3 angles of these types of triangle is exactly equal to 180 °. Further there are sub parts in acute triangles meaning there are various kinds of acute triangles too. Let us see some of them.
• Equilateral acute triangle:  This type of triangle has all of its angles less than 90 ° in measure and all of its angles are equal in measure and the addition of all 3 angles is equal to 180 °. That is, each angle here measures 60 °.
• Scalene acute triangle: This type of triangle has all of its angles less than 90 ° in measure and all of its angles are unequal in measure and the addition of all 3 angles is equal to 180 °.
• Isosceles acute triangle: This type of triangle has all of its angles less than 90 ° in measure and two of its angles are equal in measure and the addition of all 3 angles is equal to 180 °.
• Obtuse triangle: These are the triangles which have one of their angles measuring more than 90 °. The thing to be noted here is that the remaining two angles should compulsorily measure less than 90 ° and not beyond that. The addition of all 3 angles of these types of triangle is exactly equal to 180 °.
• Scalene triangle: These are the types of triangles having all of their angles different in measure. Since all of the angles are unequal in measure, so are all of the sides. The addition of all 3 angles of these types of triangle is exactly equal to 180 °.
• Equilateral triangle: These are the types of triangles having all of their angles measuring equal. Since the entire lot of angle is equal in measure so all the sides are also equal in measure. Here each angle is equal to 60 ° in measure. The addition of all 3 angles of these types of triangle is exactly equal to 180 °.
• Isosceles triangle: These are the types of triangle having two of its angles measuring equal in length and one different. Since two sides measure equal in length, so do two of its sides. The addition of all 3 angles of these types of triangle is exactly equal to 180 °.

## Conclusion:

Retrospection of the facts and details mentioned above fetches unique insights and a lot of new information on types of triangles and their properties. Additionally, we have also seen the uses of triangles in different topics of mathematics.  For more knowledge on triangles and its types, you can ask the experts at Cuemath.