Which of the following is true in a triangle `ABC?`

Options

A. (a) `(b+c)sin.(B-C)/(2)=2acos.(A)/(2)`
B. (b) `(b+c)cos.(A)/(2)=2asin.(B-C)/(2)`
C. (c) `(b-c)cos.(A)/(2)=asin.(B-C)/(2)`
D. (d) `(b-c)sin.(B-C)/(2)=2acos.(A)/(2)`

Answer

C