Question

Show that bcos^2B/2
+ c cos^2 B/2 =1

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Answer 1

Step-by-step explanation:

a[(1 + cos A)/2] + b[(1 + cos B)/2] + c[(1 + cos C)/2]

= s + (1/2) [2R sin A . cos A + 2R sin B . cos B + 2R sin C . cos C]

= s + (R/2) [sin 2A + sin 2B + sin 2C]

= s + (R/2) [4 sin A . sin B . sin C] s-2a-2-bcos-2b-2-ccos-2c-2-s-a-2