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Description: The inner product of a vector with itself is the square of the vector's norm. Equation I4 of Ponnusamy p. 362. (Contributed by NM, 1-Feb-2007) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | ipid.1 | |- X = ( BaseSet ` U ) |
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| ipid.6 | |- N = ( normCV ` U ) |
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| ipid.7 | |- P = ( .iOLD ` U ) |
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| Assertion | ipidsq | |- ( ( U e. NrmCVec /\ A e. X ) -> ( A P A ) = ( ( N ` A ) ^ 2 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ipid.1 | |- X = ( BaseSet ` U ) |
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| 2 | ipid.6 | |- N = ( normCV ` U ) |
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| 3 | ipid.7 | |- P = ( .iOLD ` U ) |
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| 4 | eqid | |- ( +v ` U ) = ( +v ` U ) |
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| 5 | eqid | |- ( .sOLD ` U ) = ( .sOLD ` U ) |
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| 6 | 1 4 5 2 3 | ipval2 | |- ( ( U e. NrmCVec /\ A e. X /\ A e. X ) -> ( A P A ) = ( ( ( ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) ^ 2 ) ) + ( _i x. ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) ) ) / 4 ) ) |
| 7 | 6 | 3anidm23 | |- ( ( U e. NrmCVec /\ A e. X ) -> ( A P A ) = ( ( ( ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) ^ 2 ) ) + ( _i x. ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) ) ) / 4 ) ) |
| 8 | 1 4 5 | nv2 | |- ( ( U e. NrmCVec /\ A e. X ) -> ( A ( +v ` U ) A ) = ( 2 ( .sOLD ` U ) A ) ) |
| 9 | 8 | fveq2d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( A ( +v ` U ) A ) ) = ( N ` ( 2 ( .sOLD ` U ) A ) ) ) |
| 10 | 2re | |- 2 e. RR |
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| 11 | 0le2 | |- 0 <_ 2 |
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| 12 | 10 11 | pm3.2i | |- ( 2 e. RR /\ 0 <_ 2 ) |
| 13 | 1 5 2 | nvsge0 | |- ( ( U e. NrmCVec /\ ( 2 e. RR /\ 0 <_ 2 ) /\ A e. X ) -> ( N ` ( 2 ( .sOLD ` U ) A ) ) = ( 2 x. ( N ` A ) ) ) |
| 14 | 12 13 | mp3an2 | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( 2 ( .sOLD ` U ) A ) ) = ( 2 x. ( N ` A ) ) ) |
| 15 | 9 14 | eqtrd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( A ( +v ` U ) A ) ) = ( 2 x. ( N ` A ) ) ) |
| 16 | 15 | oveq1d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) = ( ( 2 x. ( N ` A ) ) ^ 2 ) ) |
| 17 | 1 2 | nvcl | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` A ) e. RR ) |
| 18 | 17 | recnd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` A ) e. CC ) |
| 19 | 2cn | |- 2 e. CC |
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| 20 | 2nn0 | |- 2 e. NN0 |
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| 21 | mulexp | |- ( ( 2 e. CC /\ ( N ` A ) e. CC /\ 2 e. NN0 ) -> ( ( 2 x. ( N ` A ) ) ^ 2 ) = ( ( 2 ^ 2 ) x. ( ( N ` A ) ^ 2 ) ) ) |
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| 22 | 19 20 21 | mp3an13 | |- ( ( N ` A ) e. CC -> ( ( 2 x. ( N ` A ) ) ^ 2 ) = ( ( 2 ^ 2 ) x. ( ( N ` A ) ^ 2 ) ) ) |
| 23 | 18 22 | syl | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 2 x. ( N ` A ) ) ^ 2 ) = ( ( 2 ^ 2 ) x. ( ( N ` A ) ^ 2 ) ) ) |
| 24 | sq2 | |- ( 2 ^ 2 ) = 4 |
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| 25 | 24 | oveq1i | |- ( ( 2 ^ 2 ) x. ( ( N ` A ) ^ 2 ) ) = ( 4 x. ( ( N ` A ) ^ 2 ) ) |
| 26 | 23 25 | eqtrdi | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 2 x. ( N ` A ) ) ^ 2 ) = ( 4 x. ( ( N ` A ) ^ 2 ) ) ) |
| 27 | 16 26 | eqtrd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) = ( 4 x. ( ( N ` A ) ^ 2 ) ) ) |
| 28 | eqid | |- ( 0vec ` U ) = ( 0vec ` U ) |
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| 29 | 1 4 5 28 | nvrinv | |- ( ( U e. NrmCVec /\ A e. X ) -> ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) = ( 0vec ` U ) ) |
| 30 | 29 | fveq2d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) = ( N ` ( 0vec ` U ) ) ) |
| 31 | 28 2 | nvz0 | |- ( U e. NrmCVec -> ( N ` ( 0vec ` U ) ) = 0 ) |
| 32 | 31 | adantr | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( 0vec ` U ) ) = 0 ) |
| 33 | 30 32 | eqtrd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) = 0 ) |
| 34 | 33 | sq0id | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) ^ 2 ) = 0 ) |
| 35 | 27 34 | oveq12d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) ^ 2 ) ) = ( ( 4 x. ( ( N ` A ) ^ 2 ) ) - 0 ) ) |
| 36 | 4cn | |- 4 e. CC |
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| 37 | 18 | sqcld | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( N ` A ) ^ 2 ) e. CC ) |
| 38 | mulcl | |- ( ( 4 e. CC /\ ( ( N ` A ) ^ 2 ) e. CC ) -> ( 4 x. ( ( N ` A ) ^ 2 ) ) e. CC ) |
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| 39 | 36 37 38 | sylancr | |- ( ( U e. NrmCVec /\ A e. X ) -> ( 4 x. ( ( N ` A ) ^ 2 ) ) e. CC ) |
| 40 | 39 | subid1d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 4 x. ( ( N ` A ) ^ 2 ) ) - 0 ) = ( 4 x. ( ( N ` A ) ^ 2 ) ) ) |
| 41 | 35 40 | eqtrd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) ^ 2 ) ) = ( 4 x. ( ( N ` A ) ^ 2 ) ) ) |
| 42 | 1re | |- 1 e. RR |
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| 43 | neg1rr | |- -u 1 e. RR |
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| 44 | absreim | |- ( ( 1 e. RR /\ -u 1 e. RR ) -> ( abs ` ( 1 + ( _i x. -u 1 ) ) ) = ( sqrt ` ( ( 1 ^ 2 ) + ( -u 1 ^ 2 ) ) ) ) |
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| 45 | 42 43 44 | mp2an | |- ( abs ` ( 1 + ( _i x. -u 1 ) ) ) = ( sqrt ` ( ( 1 ^ 2 ) + ( -u 1 ^ 2 ) ) ) |
| 46 | ax-icn | |- _i e. CC |
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| 47 | ax-1cn | |- 1 e. CC |
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| 48 | 46 47 | mulneg2i | |- ( _i x. -u 1 ) = -u ( _i x. 1 ) |
| 49 | 46 | mulridi | |- ( _i x. 1 ) = _i |
| 50 | 49 | negeqi | |- -u ( _i x. 1 ) = -u _i |
| 51 | 48 50 | eqtri | |- ( _i x. -u 1 ) = -u _i |
| 52 | 51 | oveq2i | |- ( 1 + ( _i x. -u 1 ) ) = ( 1 + -u _i ) |
| 53 | 52 | fveq2i | |- ( abs ` ( 1 + ( _i x. -u 1 ) ) ) = ( abs ` ( 1 + -u _i ) ) |
| 54 | sqneg | |- ( 1 e. CC -> ( -u 1 ^ 2 ) = ( 1 ^ 2 ) ) |
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| 55 | 47 54 | ax-mp | |- ( -u 1 ^ 2 ) = ( 1 ^ 2 ) |
| 56 | 55 | oveq2i | |- ( ( 1 ^ 2 ) + ( -u 1 ^ 2 ) ) = ( ( 1 ^ 2 ) + ( 1 ^ 2 ) ) |
| 57 | 56 | fveq2i | |- ( sqrt ` ( ( 1 ^ 2 ) + ( -u 1 ^ 2 ) ) ) = ( sqrt ` ( ( 1 ^ 2 ) + ( 1 ^ 2 ) ) ) |
| 58 | 45 53 57 | 3eqtr3i | |- ( abs ` ( 1 + -u _i ) ) = ( sqrt ` ( ( 1 ^ 2 ) + ( 1 ^ 2 ) ) ) |
| 59 | absreim | |- ( ( 1 e. RR /\ 1 e. RR ) -> ( abs ` ( 1 + ( _i x. 1 ) ) ) = ( sqrt ` ( ( 1 ^ 2 ) + ( 1 ^ 2 ) ) ) ) |
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| 60 | 42 42 59 | mp2an | |- ( abs ` ( 1 + ( _i x. 1 ) ) ) = ( sqrt ` ( ( 1 ^ 2 ) + ( 1 ^ 2 ) ) ) |
| 61 | 49 | oveq2i | |- ( 1 + ( _i x. 1 ) ) = ( 1 + _i ) |
| 62 | 61 | fveq2i | |- ( abs ` ( 1 + ( _i x. 1 ) ) ) = ( abs ` ( 1 + _i ) ) |
| 63 | 58 60 62 | 3eqtr2i | |- ( abs ` ( 1 + -u _i ) ) = ( abs ` ( 1 + _i ) ) |
| 64 | 63 | oveq1i | |- ( ( abs ` ( 1 + -u _i ) ) x. ( N ` A ) ) = ( ( abs ` ( 1 + _i ) ) x. ( N ` A ) ) |
| 65 | negicn | |- -u _i e. CC |
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| 66 | 47 65 | addcli | |- ( 1 + -u _i ) e. CC |
| 67 | 1 5 2 | nvs | |- ( ( U e. NrmCVec /\ ( 1 + -u _i ) e. CC /\ A e. X ) -> ( N ` ( ( 1 + -u _i ) ( .sOLD ` U ) A ) ) = ( ( abs ` ( 1 + -u _i ) ) x. ( N ` A ) ) ) |
| 68 | 66 67 | mp3an2 | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( ( 1 + -u _i ) ( .sOLD ` U ) A ) ) = ( ( abs ` ( 1 + -u _i ) ) x. ( N ` A ) ) ) |
| 69 | 47 46 | addcli | |- ( 1 + _i ) e. CC |
| 70 | 1 5 2 | nvs | |- ( ( U e. NrmCVec /\ ( 1 + _i ) e. CC /\ A e. X ) -> ( N ` ( ( 1 + _i ) ( .sOLD ` U ) A ) ) = ( ( abs ` ( 1 + _i ) ) x. ( N ` A ) ) ) |
| 71 | 69 70 | mp3an2 | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( ( 1 + _i ) ( .sOLD ` U ) A ) ) = ( ( abs ` ( 1 + _i ) ) x. ( N ` A ) ) ) |
| 72 | 64 68 71 | 3eqtr4a | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( ( 1 + -u _i ) ( .sOLD ` U ) A ) ) = ( N ` ( ( 1 + _i ) ( .sOLD ` U ) A ) ) ) |
| 73 | 1 4 5 | nvdir | |- ( ( U e. NrmCVec /\ ( 1 e. CC /\ -u _i e. CC /\ A e. X ) ) -> ( ( 1 + -u _i ) ( .sOLD ` U ) A ) = ( ( 1 ( .sOLD ` U ) A ) ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) |
| 74 | 47 73 | mp3anr1 | |- ( ( U e. NrmCVec /\ ( -u _i e. CC /\ A e. X ) ) -> ( ( 1 + -u _i ) ( .sOLD ` U ) A ) = ( ( 1 ( .sOLD ` U ) A ) ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) |
| 75 | 65 74 | mpanr1 | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 1 + -u _i ) ( .sOLD ` U ) A ) = ( ( 1 ( .sOLD ` U ) A ) ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) |
| 76 | 1 5 | nvsid | |- ( ( U e. NrmCVec /\ A e. X ) -> ( 1 ( .sOLD ` U ) A ) = A ) |
| 77 | 76 | oveq1d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 1 ( .sOLD ` U ) A ) ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) = ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) |
| 78 | 75 77 | eqtrd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 1 + -u _i ) ( .sOLD ` U ) A ) = ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) |
| 79 | 78 | fveq2d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( ( 1 + -u _i ) ( .sOLD ` U ) A ) ) = ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ) |
| 80 | 1 4 5 | nvdir | |- ( ( U e. NrmCVec /\ ( 1 e. CC /\ _i e. CC /\ A e. X ) ) -> ( ( 1 + _i ) ( .sOLD ` U ) A ) = ( ( 1 ( .sOLD ` U ) A ) ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) |
| 81 | 47 80 | mp3anr1 | |- ( ( U e. NrmCVec /\ ( _i e. CC /\ A e. X ) ) -> ( ( 1 + _i ) ( .sOLD ` U ) A ) = ( ( 1 ( .sOLD ` U ) A ) ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) |
| 82 | 46 81 | mpanr1 | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 1 + _i ) ( .sOLD ` U ) A ) = ( ( 1 ( .sOLD ` U ) A ) ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) |
| 83 | 76 | oveq1d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 1 ( .sOLD ` U ) A ) ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) = ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) |
| 84 | 82 83 | eqtrd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 1 + _i ) ( .sOLD ` U ) A ) = ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) |
| 85 | 84 | fveq2d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( ( 1 + _i ) ( .sOLD ` U ) A ) ) = ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ) |
| 86 | 72 79 85 | 3eqtr3d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) = ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ) |
| 87 | 86 | oveq1d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) = ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) |
| 88 | 87 | oveq2d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) = ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) ) |
| 89 | 1 4 5 2 3 | ipval2lem4 | |- ( ( ( U e. NrmCVec /\ A e. X /\ A e. X ) /\ _i e. CC ) -> ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) e. CC ) |
| 90 | 46 89 | mpan2 | |- ( ( U e. NrmCVec /\ A e. X /\ A e. X ) -> ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) e. CC ) |
| 91 | 90 | 3anidm23 | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) e. CC ) |
| 92 | 91 | subidd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) = 0 ) |
| 93 | 88 92 | eqtrd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) = 0 ) |
| 94 | 93 | oveq2d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( _i x. ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) ) = ( _i x. 0 ) ) |
| 95 | it0e0 | |- ( _i x. 0 ) = 0 |
|
| 96 | 94 95 | eqtrdi | |- ( ( U e. NrmCVec /\ A e. X ) -> ( _i x. ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) ) = 0 ) |
| 97 | 41 96 | oveq12d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) ^ 2 ) ) + ( _i x. ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) ) ) = ( ( 4 x. ( ( N ` A ) ^ 2 ) ) + 0 ) ) |
| 98 | 39 | addridd | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 4 x. ( ( N ` A ) ^ 2 ) ) + 0 ) = ( 4 x. ( ( N ` A ) ^ 2 ) ) ) |
| 99 | 97 98 | eqtr2d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( 4 x. ( ( N ` A ) ^ 2 ) ) = ( ( ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) ^ 2 ) ) + ( _i x. ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) ) ) ) |
| 100 | 99 | oveq1d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 4 x. ( ( N ` A ) ^ 2 ) ) / 4 ) = ( ( ( ( ( N ` ( A ( +v ` U ) A ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u 1 ( .sOLD ` U ) A ) ) ) ^ 2 ) ) + ( _i x. ( ( ( N ` ( A ( +v ` U ) ( _i ( .sOLD ` U ) A ) ) ) ^ 2 ) - ( ( N ` ( A ( +v ` U ) ( -u _i ( .sOLD ` U ) A ) ) ) ^ 2 ) ) ) ) / 4 ) ) |
| 101 | 4ne0 | |- 4 =/= 0 |
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| 102 | divcan3 | |- ( ( ( ( N ` A ) ^ 2 ) e. CC /\ 4 e. CC /\ 4 =/= 0 ) -> ( ( 4 x. ( ( N ` A ) ^ 2 ) ) / 4 ) = ( ( N ` A ) ^ 2 ) ) |
|
| 103 | 36 101 102 | mp3an23 | |- ( ( ( N ` A ) ^ 2 ) e. CC -> ( ( 4 x. ( ( N ` A ) ^ 2 ) ) / 4 ) = ( ( N ` A ) ^ 2 ) ) |
| 104 | 37 103 | syl | |- ( ( U e. NrmCVec /\ A e. X ) -> ( ( 4 x. ( ( N ` A ) ^ 2 ) ) / 4 ) = ( ( N ` A ) ^ 2 ) ) |
| 105 | 7 100 104 | 3eqtr2d | |- ( ( U e. NrmCVec /\ A e. X ) -> ( A P A ) = ( ( N ` A ) ^ 2 ) ) |