I noticed that many mathematics textbooks designed specifically for economics students like for example Essential Mathematics for Economic Analysis - Knut Sydsaeter / Peter Hammond / Arne Strom / Andrés Carvajal do not cover trigonometric functions their derivatives and so on.
Does this mean that in economics these functions are not used at all or only rarely? Are they some special topics in economics where they are important? I am trying to decide if I should still learn them or just ignore them.
