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Lesson 7 of 11

What each stage really does

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8 min

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Put a small bump on every side of a triangle. Then do it again on the new sides. The bump is an equilateral triangle, one with three equal sides. Start with sides 1 unit long. The outline is the length all the way around the shape.

One straight side, 1 unit long.
Step 1 of 4
  1. One straight side, 1 unit long.
  2. Cut it into 3. Build a bump on the middle part.
  3. Do it again on each of the 4 pieces.
  4. The outline is 4/3 as long, every step.

Rule: Cut each side into 3 equal parts. Build an equilateral triangle on the middle part. Remove that middle part. Repeat on every new side.

The snowflake rule, with sides counted and the outline measured at each step
StepSidesOutline in units
033
1124
24816/3
319264/9

Every side becomes 4 sides. Each new side is 1/3 as long. Four new sides make 4 × 1/3 = 4/3 of one old side. So the outline grows 4/3 times each step. The shape this rule builds is the Koch snowflake.

Tap Run the rule. Watch the sides and the outline grow.

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