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Grade 11Trigonometry

sin2A/2+sin2B/2+sin2C/2 are in hp then prove that a,b,c are in hp

Profile image of sai teja
11 Years agoGrade 11
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2 Answers

Profile image of Ravi
11 Years ago
Write the AP average term in context to the HP given :
1/Sin2A/2, 1/Sin2B/2, 1/Sin2C/2...(AP)
Write the average of this AP.
Convert Sin2X/2= (1-cosX)/2

Use the cosine law to indulge the sides a,b,c into the eqn.
Simplify to get the answer.
Profile image of Vasudevamurthy
8 Years ago
http://www.askiitians.com/forums/Trigonometry/sin-2-a-2-sin-2-b-2-sin-2-c-2-are-in-hp-then-prove that a,b,c are in hp