Historical clue formulations

• Trig ratio — 2026-01-22
• Sine's reciprocal, in trig — 2025-12-28
• Trig function — 2019-08-03
• Trig ratio — 2019-07-15
• Trig function — 2018-11-11
• Sine's reciprocal, in trig — 2017-11-22
• Sine's reciprocal, briefly — 2017-11-15
• Trig ratio — 2014-04-22
• Reciprocal function in trig — 2011-12-04
• Trig. function — 2003-03-20
• Trig function — 1997-10-04
• Trig. function — 1997-06-25