A2A3=2^1/2a+b
A3A4=2^1/2A2A3+A2A1=(2^1/2)(2^1/2a+b)-a=2a+(2^1/2)b-a=a+(2^1/2)b
A4A5=2^1/2A3A4+A3A2=2^1/2(a+(2^1/2)b)-(2^1/2a+b)=2^1/2a+2b-2^1/2a-b=b
A5A6=2^1/2A4A5+A4A3=2^1/2b-a-(2^1/2)b=-a
A6A7=2^1/2A5A6+A5A4=2^1/2(-a)-b=-2^1/2a-b
A7A8=2^1/2A6A7+A6A5=2^1/2(-2^1/2a-b)+a=-2a-2^1/2b+a=-a-2^1/2