123

( a 2 + b 2 ) = ( a 2 ) + ( b 2 )

234

( b 2 + c 2 ) = ( b 2 ) + ( c 2 )

341

( a 2 + b 2 + c 2 ) = ( a 2 + b 2 ) + ( c 2 )

412

( a 2 + b 2 + c 2 ) = ( a 2 ) + ( b 2 + c 2 )