Historical clue formulations

• Odds, e.g. — 2014-05-29
• Sine and cosine — 2010-02-07
• Photoshop options — 2008-04-27
• Secants and cosecants — 2004-10-29
• Expressions with colons — 2003-02-08
• Sine and cosine — 2000-12-22
• Stock figures — 2000-03-19
• Sine, cosine and tangent — 1997-09-21
• Math figures — 1995-09-10