| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fveecn |  |-  ( ( C e. ( EE ` N ) /\ i e. ( 1 ... N ) ) -> ( C ` i ) e. CC ) | 
						
							| 2 |  | subid |  |-  ( ( C ` i ) e. CC -> ( ( C ` i ) - ( C ` i ) ) = 0 ) | 
						
							| 3 | 2 | sq0id |  |-  ( ( C ` i ) e. CC -> ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) = 0 ) | 
						
							| 4 | 1 3 | syl |  |-  ( ( C e. ( EE ` N ) /\ i e. ( 1 ... N ) ) -> ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) = 0 ) | 
						
							| 5 | 4 | sumeq2dv |  |-  ( C e. ( EE ` N ) -> sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) 0 ) | 
						
							| 6 |  | fzfid |  |-  ( C e. ( EE ` N ) -> ( 1 ... N ) e. Fin ) | 
						
							| 7 |  | sumz |  |-  ( ( ( 1 ... N ) C_ ( ZZ>= ` 1 ) \/ ( 1 ... N ) e. Fin ) -> sum_ i e. ( 1 ... N ) 0 = 0 ) | 
						
							| 8 | 7 | olcs |  |-  ( ( 1 ... N ) e. Fin -> sum_ i e. ( 1 ... N ) 0 = 0 ) | 
						
							| 9 | 6 8 | syl |  |-  ( C e. ( EE ` N ) -> sum_ i e. ( 1 ... N ) 0 = 0 ) | 
						
							| 10 | 5 9 | eqtrd |  |-  ( C e. ( EE ` N ) -> sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) = 0 ) | 
						
							| 11 | 10 | 3ad2ant3 |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) = 0 ) | 
						
							| 12 | 11 | eqeq2d |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> ( sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) <-> sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 ) ) | 
						
							| 13 |  | fzfid |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) -> ( 1 ... N ) e. Fin ) | 
						
							| 14 |  | fveere |  |-  ( ( A e. ( EE ` N ) /\ i e. ( 1 ... N ) ) -> ( A ` i ) e. RR ) | 
						
							| 15 | 14 | adantlr |  |-  ( ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ i e. ( 1 ... N ) ) -> ( A ` i ) e. RR ) | 
						
							| 16 |  | fveere |  |-  ( ( B e. ( EE ` N ) /\ i e. ( 1 ... N ) ) -> ( B ` i ) e. RR ) | 
						
							| 17 | 16 | adantll |  |-  ( ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ i e. ( 1 ... N ) ) -> ( B ` i ) e. RR ) | 
						
							| 18 | 15 17 | resubcld |  |-  ( ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ i e. ( 1 ... N ) ) -> ( ( A ` i ) - ( B ` i ) ) e. RR ) | 
						
							| 19 | 18 | resqcld |  |-  ( ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ i e. ( 1 ... N ) ) -> ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) e. RR ) | 
						
							| 20 | 18 | sqge0d |  |-  ( ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ i e. ( 1 ... N ) ) -> 0 <_ ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) ) | 
						
							| 21 | 13 19 20 | fsum00 |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) -> ( sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> A. i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 ) ) | 
						
							| 22 |  | fveecn |  |-  ( ( A e. ( EE ` N ) /\ i e. ( 1 ... N ) ) -> ( A ` i ) e. CC ) | 
						
							| 23 |  | fveecn |  |-  ( ( B e. ( EE ` N ) /\ i e. ( 1 ... N ) ) -> ( B ` i ) e. CC ) | 
						
							| 24 |  | subcl |  |-  ( ( ( A ` i ) e. CC /\ ( B ` i ) e. CC ) -> ( ( A ` i ) - ( B ` i ) ) e. CC ) | 
						
							| 25 |  | sqeq0 |  |-  ( ( ( A ` i ) - ( B ` i ) ) e. CC -> ( ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> ( ( A ` i ) - ( B ` i ) ) = 0 ) ) | 
						
							| 26 | 24 25 | syl |  |-  ( ( ( A ` i ) e. CC /\ ( B ` i ) e. CC ) -> ( ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> ( ( A ` i ) - ( B ` i ) ) = 0 ) ) | 
						
							| 27 |  | subeq0 |  |-  ( ( ( A ` i ) e. CC /\ ( B ` i ) e. CC ) -> ( ( ( A ` i ) - ( B ` i ) ) = 0 <-> ( A ` i ) = ( B ` i ) ) ) | 
						
							| 28 | 26 27 | bitrd |  |-  ( ( ( A ` i ) e. CC /\ ( B ` i ) e. CC ) -> ( ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> ( A ` i ) = ( B ` i ) ) ) | 
						
							| 29 | 22 23 28 | syl2an |  |-  ( ( ( A e. ( EE ` N ) /\ i e. ( 1 ... N ) ) /\ ( B e. ( EE ` N ) /\ i e. ( 1 ... N ) ) ) -> ( ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> ( A ` i ) = ( B ` i ) ) ) | 
						
							| 30 | 29 | anandirs |  |-  ( ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ i e. ( 1 ... N ) ) -> ( ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> ( A ` i ) = ( B ` i ) ) ) | 
						
							| 31 | 30 | ralbidva |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) -> ( A. i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> A. i e. ( 1 ... N ) ( A ` i ) = ( B ` i ) ) ) | 
						
							| 32 | 21 31 | bitrd |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) -> ( sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> A. i e. ( 1 ... N ) ( A ` i ) = ( B ` i ) ) ) | 
						
							| 33 | 32 | 3adant3 |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> ( sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = 0 <-> A. i e. ( 1 ... N ) ( A ` i ) = ( B ` i ) ) ) | 
						
							| 34 | 12 33 | bitrd |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> ( sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) <-> A. i e. ( 1 ... N ) ( A ` i ) = ( B ` i ) ) ) | 
						
							| 35 |  | simp1 |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> A e. ( EE ` N ) ) | 
						
							| 36 |  | simp2 |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> B e. ( EE ` N ) ) | 
						
							| 37 |  | simp3 |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> C e. ( EE ` N ) ) | 
						
							| 38 |  | brcgr |  |-  ( ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ C e. ( EE ` N ) ) ) -> ( <. A , B >. Cgr <. C , C >. <-> sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) ) ) | 
						
							| 39 | 35 36 37 37 38 | syl22anc |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> ( <. A , B >. Cgr <. C , C >. <-> sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( C ` i ) ) ^ 2 ) ) ) | 
						
							| 40 |  | eqeefv |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) -> ( A = B <-> A. i e. ( 1 ... N ) ( A ` i ) = ( B ` i ) ) ) | 
						
							| 41 | 40 | 3adant3 |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> ( A = B <-> A. i e. ( 1 ... N ) ( A ` i ) = ( B ` i ) ) ) | 
						
							| 42 | 34 39 41 | 3bitr4d |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> ( <. A , B >. Cgr <. C , C >. <-> A = B ) ) | 
						
							| 43 | 42 | biimpd |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) -> ( <. A , B >. Cgr <. C , C >. -> A = B ) ) | 
						
							| 44 | 43 | adantl |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) ) -> ( <. A , B >. Cgr <. C , C >. -> A = B ) ) |