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Grade: 11 

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

Answers : (2)

Saurabh Koranglekar
askIITians Faculty
8397 Points 
							Dear student

Using the standard result

576-1066_Screenshot_2019-09-29-21-00-05-246_com.android.chrome.png
one year ago
Vikas TU
12154 Points 
							
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 
 
one year ago
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