"SOHCAHTOA" is a helpful mnemonic for remembering the definitions of the trigonometric functions sine, cosine, and tangent i.e., sine equals opposite over hypotenuse, cosine equals adjacent over hypotenuse, and tangent equals opposite over adjacent,
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(1)
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(2)
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(3)
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Other mnemonics include
1. "Tommy On A Ship Of His Caught A Herring" (probably more common in Great Britain than the United States).
2. "Oscar Has A Hold On Angie."
3. "Oscar Had A Heap of Apples."
4. "The Old Army Colonel And His Son Often Hiccup" (which gives the functions in the order tangent, cosine, sine).
5. "Studying Our Homework Can Always Help To Obtain Achievement."
6. "Some Old Hippy Caught Another Hippy Tripping On Acid."
