Grade 11Trigonometry
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
2 Answers
Saurabh Koranglekar
Dear student
Using the standard result
Using the standard result
Vikas TU
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
=> 1+ 4R SinA/2 *SinB/2 *SinC/2
=> 1+ r/R
Hence prooved
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