if a + a = 180, then a = 90

Start from the conclusion and work back up the proof. Click the arrow to show the parents.

• a = 90,

  if a ⋅ 2 = 180, then a = 90

  • a ⋅ 2 = 180,

    if the following are true:

    • a = b
    • a = c

    then b = c

    • a + a = a ⋅ 2, a + a = a ⋅ 2
    • a + a = 180