Possible Clues:

• Derivative work, for short?
• HS class with integrals
• Subj. for which trig is a prereq
• Subj. with AB and BC AP tests
• High-level math, informally
• College math, informally
• Integral course of study, briefly?
• Course taken after trig, often
• Subj. with Riemann sums
• College math class