Perimeter of 2D Shapes

learning_notes

Last updated: 8/16/2025

Key Concepts:

  • Perimeter of a Rectangle: Rectangles have opposite sides equal, (P = 2(l + w)). Squares have four sides equal.
  • Perimeter of a Triangle: Sum of its three sides. Isoceles triangles have two sides equal. Equilateral triangles have three sides equal.
  • Perimeter (Circumference) of a Circle: Given radius ((r)), (C = 2\pi r). Given diameter ((d = 2r)), (C = \pi d).

Skills Covered:

  • Calculating the perimeter of a 2D shape (circles, triangles, rectangles).
  • Determining the side length of a triangle/rectangle given its perimeter.

Example Problems:

  • What is the perimeter of a square with the side length of 8?
  • A circle has a radius of 2. What is the circumference of the circle?
  • What is the side length of an equilateral triangle with a perimeter of 18 cm?

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