Definition: Diagonal
The segment joining either pair of opposite angles of a square, rectangle, rhombus, rhomboid , or trapezium is called a diagonal.
Mentioned in:
Propositions: 1 2
Topics: 3
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References
Adapted from CC BYSA 3.0 Sources:
 Callahan, Daniel: "Euclidâ€™s 'Elements' Redux" 2014
Adapted from (Public Domain)
 Casey, John: "The First Six Books of the Elements of Euclid"