$A$ body is in equilibrium under the action of three coplanar forces $P, Q$ and $R$ as shown in the figure. Select the correct statement.

• A
  $\frac{P}{\sin \alpha} = \frac{Q}{\sin \beta} = \frac{R}{\sin \gamma}$
• B
  $\frac{P}{\cos \alpha} = \frac{Q}{\cos \beta} = \frac{R}{\cos \gamma}$
• C
  $\frac{P}{\tan \alpha} = \frac{Q}{\tan \beta} = \frac{R}{\tan \gamma}$
• D
  $\frac{P}{\sin \beta} = \frac{Q}{\sin \gamma} = \frac{R}{\sin \alpha}$