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In a triangle ABC, CD is the bisector of...

In a triangle `ABC, CD` is the bisector of the angle C. If `cos (C/2)` has the value `1/3 and l(CD)=6,` then `(1/a+1/b)` has the value equal to -

Text Solution

Verified by Experts

The correct Answer is:
`(1)/(9)`
`Delta = Delta_(1) + Delta_(2)`
or `(1)/(2) ab sin C = (1)/(2) 6b sin.(C)/(2) + (1)/(2)6a sin.(C)/(2)`
or `ab sin.(C)/(2) cos.(C)/(2) = (1)/(2) 6b sin.(C)/(2) + (1)/(2) 6a sin.(C)/(2)`
or `(1)/(a) + (1)/(b) = (1)/(9)`
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