Historical clue formulations

• Kind of wave — 2026-07-05
• Basic trig ratio — 2026-03-30
• Math function — 2026-01-10
• Kind of wave — 2025-09-02
• ___ wave — 2025-03-30
• Trigonometry function — 2024-12-17
• 0, for 180° — 2024-08-23
• Function that can be derived from a unit circle — 2024-06-21
• Opposite side divided by the hypotenuse — 2024-06-09
• 1, for 90° — 2024-04-20
• Cosecant's reciprocal — 2024-02-25
• 0, for 180 — 2023-11-17
• Trig function — 2023-07-10
• Kind of wave — 2023-05-17
• Without: Lat. — 2022-10-02
• ___ wave — 2022-09-16
• Wave to one's math professor? — 2022-08-28
• Kind of wave — 2022-03-05
• It's 1 for 90° — 2021-12-23
• 0, for 0° — 2021-09-03
• Reciprocal of cosecant — 2021-05-07
• Ratio of an angle's opposite side to the hypotenuse — 2021-04-04
• Function yielding 0 when applied to pi — 2021-03-11
• Kind of wave — 2020-12-16
• Kind of wave — 2020-03-27
• Trig function — 2020-01-26
• Trigonometric ratio — 2019-01-14
• Basic trig ratio — 2018-12-03
• Function associated with oscillation — 2018-07-31
• ___ qua non — 2018-06-27
• ___ qua non — 2018-06-10
• ___ qua non (essential element) — 2018-03-28
• Wave to a math teacher? — 2018-01-18
• 0, for 0 degrees — 2017-08-05
• ___ wave (oscilloscope output) — 2017-05-17
• Trig function — 2017-02-14
• Kind of wave — 2016-10-14
• It makes a wave — 2016-07-15
• It's 1 for 90° — 2016-03-15
• ___ wave — 2016-02-27
• 0.5, for 150° — 2015-12-26
• Wave creator — 2015-06-19
• ___ qua non — 2015-05-04
• ___ wave — 2015-03-17
• 0, for 180 degrees — 2014-12-19
• It has a reciprocal function — 2014-11-19
• 0.5, for 30 degrees — 2014-10-04
• It's between -1 and +1 — 2014-09-13
• Reciprocal of 12-Down — 2014-04-22
• ___ die — 2014-02-20