Elements I.01

Euclid's Extreme and Mean Proportion Constructions

Euclid VI.13 shows how to get a mean proportional to two other lines using a semicircle ADB.[br]Euclid II.11 shows how to cut a single line into extreme and mean proportion using squares AG and AH.[br][br]Sliding point D on the circle produces any number of three lines in extreme and mean proportion, but only when C coincides with M is the diameter cut in extreme and mean proportion.[br][br]Is there a way, using only the circle construction of VI.13, to find where pont M is such that the diameter AB is cut in extreme and mean proportion?
Euclid's Extreme and Mean Proportion Constructions

Arc and Chord Lengths in a Circle

Arc and Chord Lengths in a Circle

Logarithmic Spiral

A variation on the classic construction, with adjustable angle and number or radial rays.[br][br]Play and make some pretty things![br][br]But you can also look for exponential patterns.
Logarithmic Spiral
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