Three forces $\overrightarrow{P}, \overrightarrow{Q}$ and $\overrightarrow{R}$ acting along $IA, \; IB$ and $IC$, where $I$ is the incentre of a $\Delta ABC$, are in equilibrium. Then $\overrightarrow{P} : \overrightarrow{Q} : \overrightarrow{R}$ is

Question

( A ) $\cos \frac{A}{2} : \cos \frac{B}{2} : \cos \frac{C}{2}$
( B ) $\sin \frac{A}{2} : \sin \frac{B}{2} : \sin \frac{C}{2}$
( C ) $\mathrm{cosec} \frac{A}{2} : \mathrm{cosec} \frac{B}{2} : \mathrm{cosec} \frac{C}{2}$
( D ) $\sec \frac{A}{2} : \sec \frac{B}{2} : \sec \frac{C}{2}$