See: List of castles Castles in England
Angus
Argyll and Bute
Dumfries and Galloway
Dundee
Edinburgh
Fife
Highland
Moray
Perthshire
Scottish Borders
Stirling
... left side is now a perfect square; it is the square of (x + b/(2a)). The right side can be written as a single fraction; the common denominator is 4a2. W ...