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What is a Triangle?

What is a triangle?

Summary

  1. A triangle is a polygon made up of three angles and three sides
  2. A line segment that connects the two angles is called a side
  3. A vertex is a point where two sides meet
  4. 'A', 'B', and 'C' label the vertices of the triangle
  5. 'x', 'y', and 'z' stand for the measurements of the angles of the triangle
  6. The little circle in the angle measurements means 'degrees'
  7. The three angles of any triangle always add up to 180 degrees

Notes

    1. 'Tri' means 'three'
    2. An angle is formed when two line segments intersect each other
    3. A triangle is made up of three angles
    1. A polygon is a closed figure made up of three or more line segments
    2. A triangle is a specific kind of polygon, with three sides and three angles
    1. These line segments are the sides of the triangle
    1. The sides are the three line segments that make up the triangle
    1. Remember, a triangle always has three angles
    2. In any triangle, these three angles will ALWAYS add up to 180 degrees!
    1. 'x', 'y', and 'z' stand for the measurements of the angles of the triangle
    2. The little circle in the angle measurements means 'degrees'
    1. The Triangle Sum Theorem says that the three angles of a triangle ALWAYS add up to 180 degrees
    2. Knowing this can help you solve a lot of problems involving triangles!
    1. Triangles can be classified by their number of congruent sides or by their types of angles
    2. Two sides are congruent if they have the same length
    1. Triangles can be classified by their number of congruent sides or by their types of angles
    2. Two sides are congruent if they have the same length
    1. Acute angles are angles that measure less than 90 degrees
    2. Obtuse angles are angles that measure between 90 and 180 degrees
    3. Right angles are angles that measure exactly 90 degrees
    1. Remember, sides are line segments that makes up the edges of the triangle
    2. Two sides are congruent if they have the same length
    3. Triangles also have the same number of congruent angles as congruent sides
    4. Congruent angles are angles that have the same measurement
    5. Equilateral triangles have 3 congruent angles
    6. Isosceles triangles have 2 congruent angles
    7. Scalene triangles have no congruent angles