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Colorful geometry

This geometry book from 1847 (!!) uses “colored diagrams and symbols instead of letters for the greater ease of learners.”

For example, consider this right-angled triangle…

… and two ways of stating facts about it.

The old way (quoting from the book):

  1. The angle BAC, together with the angles BCA and ABC are equal to two right angles, or twice the angle ABC.
  2. The angle CAB added to the angle ACB will be equal to the angle ABC.
  3. The angle ABC is greater than either of the angles BAC or BCA.

And the new way:

I loved geometry in high school, but it was despite the drab textbooks. Why isn’t this the standard way geometry is taught everywhere?

You can download the entire book, or view it online.

(via Public Domain Review)

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