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if A,B,C are angles of a triangle prove that cosA + cosB + cosC = 1 + r/R

if A,B,C are angles of a triangle prove that cosA + cosB + cosC = 1 + r/R

Grade:11

2 Answers

Saurabh Koranglekar
askIITians Faculty 10335 Points
4 years ago
Dear student

Using the standard result

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Vikas TU
14149 Points
4 years ago
Dear student 
CosA + CosB +CosC = 1 + 4 SinA/2 *SinB/2 *SinC/2
=> 1+ 4R SinA/2 *SinB/2 *SinC/2
=> 1+ r/R 
Hence prooved 
 

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