Lesson 2: The Sine and Cosine Ratios - Labelling Sides

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A video describing how to label the sides of a right triangle for trigonometry and determining which trigonometric ratio to use is provided.



When you first start working with the three primary trigonometric ratios, it is easy to forget which sides of the triangle are used for each of the ratios. Some mnemonics that may help you remember are provided.

Sine = Opposite ÷ Hypotenuse

Cosine = Adjacent ÷ Hypotenuse

Tangent = Opposite ÷ Adjacent

  • SOH CAH TOA (often pronounced sew-ka-tow-a)
  • Tommy On A Ship Of His Caught A Herring.
  • The Old Army Colonel And His Son Often Hiccup.

Be sure to find a way to remember the three ratios that works for YOU.

Practice labelling the sides of a triangle by completing the following activity using the link provided.

Practice labelling the sides of a right triangle


Now, it is your turn! Complete the questions in your Chapter 4, Lesson 2 Practice Makes Perfect that refer to Labelling Sides.



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