Relations between angles and sides

Relations between angles and sides

1. use cosine law

   • plug cosine into the half angle identity
     • COS (THETA/2)
     • we get for sine half angle:
       • and for tangent half angle:
         • tangent of half angle is also equal to:
     • we get for cosine half angle:
     • since p=(a+b+c)/2
       • a+b=2p-c
         • a+c=2p-b

2. Area expressed in terms of sides and angles

   • Radii of circumscribed and inscribed circles in terms of sides and angles
   • SEMIPERIMETER=p
     • s=p
       • S=area

3. p=semiperimeter=(a+b+c)/2

4. Law of tangent

5. Law of sine

6. Median formula

7. Bisector formula

Images and files in the map

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• Properties of Triangles - Half Angles - Sin A/2, Cos A/2 and Tan A/2 etc., (Embed)
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