# Why are hyperbolic trigonometric functions avoided in (my) high school and early post-secondary school?

I remember seeing hyperbolic trigonometric functions (sinh, cosh, tanh, etc.) in my precalculus textbook back in high school and see them today in my calculus textbook. However, I have not had a formal introduction to them in my education. This may just be with me, but I would like to know if there is a reason as to why they are avoided.

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Political correctness, not enough time, lower quality students, more important topics, lousy teachers, common core chains, students more interested in instagram and kik ... – Amzoti Jan 28 '14 at 2:16
I have often wondered about that. An unfounded, undergraduate hypothesis is that right-triangle trig is more obviously applicable to physical applications that highschoolers/lower-undergrads would understand. A more likely (unfortunately) idea is the one Amzoti mentioned. – apnorton Jan 28 '14 at 2:19
when I teach calculus II I personally make a point of comparing and contrasting the hyperbolic verses trigonometric substitutions. In fact, the duality of the formulas brings added insight to both sides. But, alas, I am alone in this. – James S. Cook Jan 28 '14 at 2:21
As with many historical mysteries, this goes back to behind-the-scenes manipulations by Rodrigo Borgia, father of Lucrezia and Cesare: en.wikipedia.org/wiki/Treaty_of_Tordesillas – Will Jagy Jan 28 '14 at 2:21
Hyperbolic functions are skipped in a lot of university calculus sequences as well. An argument for doing so is that, in terms of applications, they turn up very little outside of physics and some branches of engineering. Most people can really go happily through their lives without worrying about hyperbolic functions or complex numbers. Consequently, they generally get introduced "if there's time" in first-year university math, but otherwise get covered in much detail in "upper-division courses" (with the usual "of course you've already seen this...") I don't approve either >:/ ... – RecklessReckoner Jan 28 '14 at 3:49