shape & space : Sin & Cosine Rules


the Sine Rule





The Sine Rule


sine rule


    1. Use either the right, or left hand equation.
    2. You are given 3 quantities and required to work out the 4 th.


Manipulating the ratio - Take two ratios, cross multiply and rearrange to put the required quantity as the subject of the equation.


      sine rule derivatives


Example #1

sine rule prob#1


sine rule prob#1


Example #2

sine rule probs #2


sine rule prob #2


Example #3

sin rule probs #3


sine rule prob#3


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The Cosine Rule


cosine rule


There are two problem types:

  1. You are given 2 sides + an included angle and required to work out the remaining side
  2. You are given all the sides and required to work out the angle.


Example #1

cosine rule prob #1


cosine rule prob #1


Example #2

cosine rule prob#3


cosine rule prob #2


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