Triangles

Triangles

1. The sine rule

   • a/sinA b/sinB c/sinC
     • You use this rule to work out the length of one of the sides
   • sinA/a sinB/b sinC/c
     • You can use this rule to work out the size of one of the angles
       • For example, to find angle R, you do sinR/4 = sin75/9, you multiply both sides by 4 to get sinR = sin75/9 x 4 = 0.4293. Do the inverse sine rule and you get 25.4 degrees.

2. The cosine rule

   • a2 = b2 + c2 - 2bc cosA
     • You can use this when you don't have a lot of information about a triangle
       • The equation can be written like this to find the angles

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