This article describes how mathematics may be experienced in widely different ways across mathematics and physics courses and highlights some unexpected constraints in a trigonometry curriculum. The examples and discussion are based on a study (Mateas 2020) that compares how trigonometry is portrayed in representative physics (i.e., "Holt McDougal Physics" [Serway and Faughn 2012], Active Physics [Eisenkraft 2010]) and mathematics textbooks (i.e., Holt McDougal series, CPM's Connections series). The first part of this article presents a closer look at two related tasks from textbooks in different disciplines in order to highlight how a student's mathematical experience can vary across STEM courses. The second part presents some lessons learned when comparing mathematics textbooks to physics textbooks, revealing unacknowledged conventions, new strategies, and different meanings of mathematical concepts.