IMO GP is about the labelling: Instead of a2-b2 use longer2-shorter2 (and on visual representation one side will always be longer, as per GPs explanation). Dia

IMO GP is about the labelling: Instead of a2-b2 use longer2-shorter2 (and on visual representation one side will always be longer, as per GPs explanation). Diagram doesn't show proof for "shorter2-longer2". I believe showing negative area would spark more controversy (imagine that negative area is painted orange, visual area would still be positive). Shorter2-longer2 gives you same absolute value with reverse signed, so it feels symmetric to me (can't remember what the formal definition is), i.e: 1. a2 - b2 = ( a-b)(a+b) # * -1 2. -(-a2 + b2) = -(-a+b)(a+b) 3. -(b2 - a2) = -( b-a)(b+a) # / -1 4. b2 - a2 = ( b-a)(b+a) Edit: https://imgur.com/a/olETWfr https://imgur.com/a/olETWfr - crude image with labels swap as it seems it's bringing some controversy.