The Trigonometry mnemonics reference article from the English Wikipedia on 24-Jul-2004
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Trigonometry mnemonics

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A number of mnemonics have been invented by educators to help students remember the rules defining the various trigonometric functions. Some of them are listed here, in no particular order
SOHCAHTOA (sounds like "soak a toe-a"). It reminds one that:
Old Harry Spills All His Custard Over Auntie's Tablecloth. Note that the definition phrasings are the reverse of those in the previous mnemonic.
Oh Heck, Another Hour Of Algebra!. Each pair of words refers implicitly to sine, cosine, and tangent, respectively:
Some Old Hippie Came Around Here Tripping On Acid (or "...Caught Another Hippie...")
Sally Can Tell Oscar Has A "Hat" On Always
Signs Of Happiness Come After Having Tubs Of Acid
Some Old Hags Can't Always Hide Their Old Age
Some Old Horses Can Always Hear Their Owner's Approach
Another mnemonic helps recall which functions are positive in which quadrant:

All Students Take Calculus (or a more memorable alternative, referring to any drug starting with 'c'!)