Pythagorean identities

Trigonometry Ratios-Mnemonics

• Students often use mnemonics to remember facts and relationships in trigonometry.
• For example, the sine, cosine, and tangent ratios in a right triangle can be remembered by representing them as strings of letters, as in SOH-CAH-TOA.
  Sine = Opposite ÷ Hypotenuse
  Cosine = Adjacent ÷ Hypotenuse
  Tangent = Opposite ÷ Adjacent
• Alternatively, one can devise sentences which consist of words beginning with the letters to be remembered.
• For example, to recall that Tan = Opposite/Adjacent, the letters T-O-A must be remembered. Any memorable phrase constructed of words beginning with the letters T-O-A will serve.
  
• Another type of mnemonic describes facts in a simple, memorable way, such as "Plus to the right, minus to the left; positive height, negative depth," which refers to trigonometric functions generated by a revolving line.