section_path: Writings/Surviving works/On the Equilibrium of Planes
section_name: On the Equilibrium of Planes
paragraph_text: On the Equilibrium of Planes
  
  There are two books to On the Equilibrium of Planes: the first contains seven postulates and fifteen propositions, while the second book contains ten propositions. In the first book, Archimedes proves the law of the lever, which states that:
  
  Magnitudes are in equilibrium at distances reciprocally proportional to their weights.
  
  Archimedes uses the principles derived to calculate the areas and centers of gravity of various geometric figures including triangles, parallelograms and parabolas.