|Use in other languages|
Theta (uppercase Θ / lowercase θ), is a letter in the Greek alphabet. It represents the "th" sound (as in "think") in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 9. The Cyrillic letter Ѳ came from theta.
In mathematics, the lowercase θ is used as a variable to represent an angle, and the uppercase Θ is used in big-theta notation (a variant of big-O notation). The lowercase θ is also used to represent the potential temperature in meteorology.
- "Greek/Hebrew/Latin-based Symbols in Mathematics". Math Vault. 2020-03-20. Retrieved 2020-10-06.
- "Theta Symbol in Greek Alphabet". www.greeksymbols.net. Retrieved 2020-10-06.