n
s-b\ =< a- b,a-b>= 2 (a, - bj)
i=1
n ■> n r> n
Ta* + Tb* -2 Tarty /=1 /=1 /=1
a~bf =|i|2 +|^|2 -2|ą|' |i)|oosZ(£,i))
+ b2 -2 < s,b>