The Seventeenth: Right Triangles with a Line to the Base
Three views of a right triangle, and one drawn with its base upward
The folio opens the seventeenth proposition with three views of a right triangle; in the second and third a line runs from the upper vertex down to the base, and a horizontal pen-stroke closes the demonstration. A further right triangle is drawn with its base uppermost. Only the heading 'Seventeenth' is written out, alongside faint show-through of construction lines from adjacent leaves.
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Proposition the seventeenth: a line drawn to the base
Three views of a right triangle head the seventeenth proposition, the second and third adding a line from the upper vertex to the base. A horizontal stroke of the pen concludes the consideration.
A right triangle with base upward
A further right triangle is drawn with its base placed uppermost. The inverted orientation repeats the figure for comparison with the views above.