wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

In triangle ABC, prove that cosA2+cosB2+cosC2=4cosπA4cosπB4cosπC4

Open in App
Solution

In ABC, A+B+C=π
cosA2+cosB2+cosC2=cosA2+2cosB+C4cosBC4=cosA2+2cosBC4cosπA4
=sinπA2+2cosBC4cosπA4
=2cosπA4(sinπA4+cosBC4)
=2cosπA4(cos(πB4+πC4)+cos(πB4πC4))=4cosπA4cosπB4cosπC4

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Basics of geometry
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon