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Prove that bc cos^(2).(A)/(2) + ca cos^(...

Prove that `bc cos^(2).(A)/(2) + ca cos^(2).(B)/(2) + ab cos^(2).(C)/(2) = s^(2)`

Text Solution

Verified by Experts

The correct Answer is:
2
`cos.(A)/(2) = sqrt((s(s -a))/(bc))`
or `bc cos^(2).(A)/(2) = s (s -a)`
or `bc cos^(2).(A)/(2) + ca cos^(2).(B)/(2) + ab cos^(2).(C)/(2)`
`= s (3s - (a + b + c)) = s (3s - 2s) = s^(2)`
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