section_path: Types/Combining angle pairs
section_name: Combining angle pairs
paragraph_text: Combining angle pairs
  
  The angle addition postulate states that if B is in the interior of angle AOC, then
  
  m ∠ A O C = m ∠ A O B + m ∠ B O C {\displaystyle m\angle \mathrm {AOC} =m\angle \mathrm {AOB} +m\angle \mathrm {BOC} }
  
  I.e., the measure of the angle AOC is the sum of the measure of angle AOB and the measure of angle BOC.
  
  Three special angle pairs involve the summation of angles: