Page [84]: changed "tangental" to "tangential" (tangential to the circle X)
Page [84]: changed "Q" to "2" (making G n equal to 2AG - GD)
Page [84]: added missing opening parenthesis in "(I have indicated this square by dotted lines.)"
Page [84]: changed "+ 1'25}" to "× 25" ({76'5625 + 1'5625} = {3'125 × 25})
Page [84]: changed "hypothenuse" to "hypotenuse" (the area of a square on the hypotenuse)