jee-advanced 2005 Q24

jee-advanced · India · screening Sine and Cosine Rules Determine an angle or side from a trigonometric identity/equation

24. In a $\triangle \mathrm { ABC }$, among the following which one is true?
(a) $( b + c ) \cos A / 2 = a \sin ( ( B + C ) / 2 )$
(b) $( b + c ) \cos ( ( B + C ) / 2 ) = a \sin A / 2$
(c) $( b - c ) \cos ( ( B - C ) / 2 ) = a \cos ( A / 2 )$
(d) $( b - c ) \cos A / 2 = a \cos ( ( B - C ) / 2 )$

24. In a $\triangle \mathrm { ABC }$, among the following which one is true?\\
(a) $( b + c ) \cos A / 2 = a \sin ( ( B + C ) / 2 )$\\
(b) $( b + c ) \cos ( ( B + C ) / 2 ) = a \sin A / 2$\\
(c) $( b - c ) \cos ( ( B - C ) / 2 ) = a \cos ( A / 2 )$\\
(d) $( b - c ) \cos A / 2 = a \cos ( ( B - C ) / 2 )$\\

Paper Questions

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