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Triangles are one of the basic shapes in geometry and come in several varieties. Each type of triangle is categorized based on its side lengths or angles.
Commonly, triangles are classified in two primary ways: by their sides and by their angles. When discussing types based on side lengths, there are three main triangle types:

• **Equilateral Triangle**: All sides are of equal length, and consequently, all angles are equal, typically 60 degrees each.
• **Isosceles Triangle**: This triangle has two sides that are the same length. It also comes with two equal angles opposite these sides.
• **Scalene Triangle**: All sides have different lengths, which means all angles are also distinct.

Understanding these types is critical for further exploration in geometry.

Triangle classification extends beyond just side lengths to include the angles within the triangle as well. In geometry, classification by angles helps to determine properties such as similarity and congruence.
Some important classifications based on angles include:

• **Acute Triangle**: All three angles are less than 90 degrees.
• **Right Triangle**: Has one angle exactly 90 degrees. This type of triangle follows the famous Pythagorean Theorem.
• **Obtuse Triangle**: Contains one angle greater than 90 degrees.

Each classification has different mathematical properties and applications. For example, right triangles are fundamental in trigonometry, while the properties of isosceles triangles make them interesting in symmetry studies.

Understanding the fundamentals of geometry, which include concepts like points, lines, and angles, is essential before diving into the study of triangles.
Basic geometry starts with **points**, the most fundamental unit, represented as dots that specify position but have no size. Next are **lines**, which are one-dimensional and extend infinitely in both directions. **Line segments** are parts of a line with a definite start and end.
**Angles** arise when two lines intersect. The point at which they meet is called the vertex. A key part of learning geometry basics is also understanding different types of angles:

• **Acute Angle**: Less than 90 degrees.
• **Right Angle**: Exactly 90 degrees.
• **Obtuse Angle**: Greater than 90 degrees.

These basic concepts form the building blocks for further learning and understanding of geometry, including the study of different types of triangles.