Analysis of information sources in references of the Wikipedia article "Delta (letter)" in English language version.
Dr. John Dee, a mathematician, used the lowercase Delta symbol to represent himself in manuscripts.
In astronomy, the symbol is used to represent the declination of an object.
Chord with a triangle Major 7th "C△"
Delta is the first derivative of option price with respect to underlying price S.
{{cite journal}}: Cite journal requires |journal= (help)The symmetric difference of sets A and B is variously written as A ⊖ B, A∇ B, A+B (Borowski and Borwein 1991) or AΔB (Harris and Stocker 1998, p. 3). All but the first notation should probably be deprecated since each of the other symbols has a common meaning in other areas of mathematics.