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Identify pentagons

A pentagon is a closed, two-dimensional shape made of exactly five straight line segments and five vertices, or corners. Identification depends on counting its sides and vertices rather than its size, color, orientation, or regularity, so irregularly shaped pentagons are included; measuring angles, perimeter, or area and classifying more advanced properties are not part of this understanding.

Detailed Explanation: Identify pentagons

A pentagon is a closed, flat shape with exactly:

  • 55 straight sides
  • 55 corners, also called vertices

To identify one, trace around the outside and count the sides or corners. The shape can be large, small, tilted, or uneven.

Example:

        B
      /   \
    A       C
     \     /
      E---D

Step 1: Start at corner AA and trace around the shape.

Step 2: Count the straight sides:

  1. AA to BB
  2. BB to CC
  3. CC to DD
  4. DD to EE
  5. EE to AA

Step 3: Count the corners: AA, BB, CC, DD, and EE. There are 55 corners.

Because the shape is closed and has exactly 55 straight sides and 55 corners, it is a pentagon.

Learn by doing: Identify pentagons

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Classifying Polygons by Sides


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