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Grade 11Trigonometry

prove that cos35+cos85+cos155=0.
plz sir/madam give me the full solution
Thank you

Profile image of Chinnu
6 Years agoGrade 11
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1 Answer

Profile image of Vikas TU
6 Years ago
Dear student 
Cos35 +cos85+cos 155
Cos(60-25)+cos(60+25)+cos155
2 cos60 cos 25 + cos (180-25)
2*1/2 cos25 - cos 25
Cos 25 - cos25=0

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