| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ex-fpar.h |  |-  H = ( ( `' ( 1st |` ( _V X. _V ) ) o. ( F o. ( 1st |` ( _V X. _V ) ) ) ) i^i ( `' ( 2nd |` ( _V X. _V ) ) o. ( G o. ( 2nd |` ( _V X. _V ) ) ) ) ) | 
						
							| 2 |  | ex-fpar.a |  |-  A = ( 0 [,) +oo ) | 
						
							| 3 |  | ex-fpar.b |  |-  B = RR | 
						
							| 4 |  | ex-fpar.f |  |-  F = ( sqrt |` A ) | 
						
							| 5 |  | ex-fpar.g |  |-  G = ( sin |` B ) | 
						
							| 6 |  | df-ov |  |-  ( X ( + o. H ) Y ) = ( ( + o. H ) ` <. X , Y >. ) | 
						
							| 7 |  | sqrtf |  |-  sqrt : CC --> CC | 
						
							| 8 |  | ffn |  |-  ( sqrt : CC --> CC -> sqrt Fn CC ) | 
						
							| 9 | 7 8 | ax-mp |  |-  sqrt Fn CC | 
						
							| 10 |  | rge0ssre |  |-  ( 0 [,) +oo ) C_ RR | 
						
							| 11 |  | ax-resscn |  |-  RR C_ CC | 
						
							| 12 | 10 11 | sstri |  |-  ( 0 [,) +oo ) C_ CC | 
						
							| 13 |  | fnssres |  |-  ( ( sqrt Fn CC /\ ( 0 [,) +oo ) C_ CC ) -> ( sqrt |` ( 0 [,) +oo ) ) Fn ( 0 [,) +oo ) ) | 
						
							| 14 | 2 | reseq2i |  |-  ( sqrt |` A ) = ( sqrt |` ( 0 [,) +oo ) ) | 
						
							| 15 | 14 | fneq1i |  |-  ( ( sqrt |` A ) Fn ( 0 [,) +oo ) <-> ( sqrt |` ( 0 [,) +oo ) ) Fn ( 0 [,) +oo ) ) | 
						
							| 16 | 13 15 | sylibr |  |-  ( ( sqrt Fn CC /\ ( 0 [,) +oo ) C_ CC ) -> ( sqrt |` A ) Fn ( 0 [,) +oo ) ) | 
						
							| 17 | 9 12 16 | mp2an |  |-  ( sqrt |` A ) Fn ( 0 [,) +oo ) | 
						
							| 18 |  | id |  |-  ( F = ( sqrt |` A ) -> F = ( sqrt |` A ) ) | 
						
							| 19 | 2 | a1i |  |-  ( F = ( sqrt |` A ) -> A = ( 0 [,) +oo ) ) | 
						
							| 20 | 18 19 | fneq12d |  |-  ( F = ( sqrt |` A ) -> ( F Fn A <-> ( sqrt |` A ) Fn ( 0 [,) +oo ) ) ) | 
						
							| 21 | 4 20 | ax-mp |  |-  ( F Fn A <-> ( sqrt |` A ) Fn ( 0 [,) +oo ) ) | 
						
							| 22 | 17 21 | mpbir |  |-  F Fn A | 
						
							| 23 |  | sinf |  |-  sin : CC --> CC | 
						
							| 24 |  | ffn |  |-  ( sin : CC --> CC -> sin Fn CC ) | 
						
							| 25 | 23 24 | ax-mp |  |-  sin Fn CC | 
						
							| 26 |  | fnssres |  |-  ( ( sin Fn CC /\ RR C_ CC ) -> ( sin |` RR ) Fn RR ) | 
						
							| 27 | 3 | reseq2i |  |-  ( sin |` B ) = ( sin |` RR ) | 
						
							| 28 | 27 | fneq1i |  |-  ( ( sin |` B ) Fn RR <-> ( sin |` RR ) Fn RR ) | 
						
							| 29 | 26 28 | sylibr |  |-  ( ( sin Fn CC /\ RR C_ CC ) -> ( sin |` B ) Fn RR ) | 
						
							| 30 | 25 11 29 | mp2an |  |-  ( sin |` B ) Fn RR | 
						
							| 31 |  | id |  |-  ( G = ( sin |` B ) -> G = ( sin |` B ) ) | 
						
							| 32 | 3 | a1i |  |-  ( G = ( sin |` B ) -> B = RR ) | 
						
							| 33 | 31 32 | fneq12d |  |-  ( G = ( sin |` B ) -> ( G Fn B <-> ( sin |` B ) Fn RR ) ) | 
						
							| 34 | 5 33 | ax-mp |  |-  ( G Fn B <-> ( sin |` B ) Fn RR ) | 
						
							| 35 | 30 34 | mpbir |  |-  G Fn B | 
						
							| 36 | 1 | fpar |  |-  ( ( F Fn A /\ G Fn B ) -> H = ( x e. A , y e. B |-> <. ( F ` x ) , ( G ` y ) >. ) ) | 
						
							| 37 | 22 35 36 | mp2an |  |-  H = ( x e. A , y e. B |-> <. ( F ` x ) , ( G ` y ) >. ) | 
						
							| 38 |  | opex |  |-  <. ( F ` x ) , ( G ` y ) >. e. _V | 
						
							| 39 | 37 38 | fnmpoi |  |-  H Fn ( A X. B ) | 
						
							| 40 |  | opelxpi |  |-  ( ( X e. A /\ Y e. B ) -> <. X , Y >. e. ( A X. B ) ) | 
						
							| 41 |  | fvco2 |  |-  ( ( H Fn ( A X. B ) /\ <. X , Y >. e. ( A X. B ) ) -> ( ( + o. H ) ` <. X , Y >. ) = ( + ` ( H ` <. X , Y >. ) ) ) | 
						
							| 42 | 39 40 41 | sylancr |  |-  ( ( X e. A /\ Y e. B ) -> ( ( + o. H ) ` <. X , Y >. ) = ( + ` ( H ` <. X , Y >. ) ) ) | 
						
							| 43 |  | simpl |  |-  ( ( X e. A /\ Y e. B ) -> X e. A ) | 
						
							| 44 |  | simpr |  |-  ( ( X e. A /\ Y e. B ) -> Y e. B ) | 
						
							| 45 | 37 43 44 | fvproj |  |-  ( ( X e. A /\ Y e. B ) -> ( H ` <. X , Y >. ) = <. ( F ` X ) , ( G ` Y ) >. ) | 
						
							| 46 | 45 | fveq2d |  |-  ( ( X e. A /\ Y e. B ) -> ( + ` ( H ` <. X , Y >. ) ) = ( + ` <. ( F ` X ) , ( G ` Y ) >. ) ) | 
						
							| 47 |  | df-ov |  |-  ( ( F ` X ) + ( G ` Y ) ) = ( + ` <. ( F ` X ) , ( G ` Y ) >. ) | 
						
							| 48 | 4 | fveq1i |  |-  ( F ` X ) = ( ( sqrt |` A ) ` X ) | 
						
							| 49 |  | fvres |  |-  ( X e. A -> ( ( sqrt |` A ) ` X ) = ( sqrt ` X ) ) | 
						
							| 50 | 48 49 | eqtrid |  |-  ( X e. A -> ( F ` X ) = ( sqrt ` X ) ) | 
						
							| 51 | 5 | fveq1i |  |-  ( G ` Y ) = ( ( sin |` B ) ` Y ) | 
						
							| 52 |  | fvres |  |-  ( Y e. B -> ( ( sin |` B ) ` Y ) = ( sin ` Y ) ) | 
						
							| 53 | 51 52 | eqtrid |  |-  ( Y e. B -> ( G ` Y ) = ( sin ` Y ) ) | 
						
							| 54 | 50 53 | oveqan12d |  |-  ( ( X e. A /\ Y e. B ) -> ( ( F ` X ) + ( G ` Y ) ) = ( ( sqrt ` X ) + ( sin ` Y ) ) ) | 
						
							| 55 | 47 54 | eqtr3id |  |-  ( ( X e. A /\ Y e. B ) -> ( + ` <. ( F ` X ) , ( G ` Y ) >. ) = ( ( sqrt ` X ) + ( sin ` Y ) ) ) | 
						
							| 56 | 42 46 55 | 3eqtrd |  |-  ( ( X e. A /\ Y e. B ) -> ( ( + o. H ) ` <. X , Y >. ) = ( ( sqrt ` X ) + ( sin ` Y ) ) ) | 
						
							| 57 | 6 56 | eqtrid |  |-  ( ( X e. A /\ Y e. B ) -> ( X ( + o. H ) Y ) = ( ( sqrt ` X ) + ( sin ` Y ) ) ) |