About "tg" vs "tan": for a while, "tg", "cotg", and "cosec" were used.
Then the academic community switched to "tan", "cot", and "csc" but the
high school trigonometry textbooks remained with "tg" and family. After
a while, the high school textbooks also switched. Now the common form
used in all levels of education is "tan" and family.
About the stretched limit: High schools used that Persian stretched
limit (Heh, Dal) when I was in high school, but the official textbooks
now use the Latin "lim" (I just confirmed this with a high school
student who checked with his textbook). The academic community have
often used "lim".
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