if (distance BC) ⋅ (distance BC) = ((distance AB) ⋅ (distance AB)) + ((distance AC) ⋅ (distance AC)), then (distance CB) ⋅ (distance CB) = ((distance CA) ⋅ (distance CA)) + ((distance AB) ⋅ (distance AB))

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