| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 2itscp.a |  |-  ( ph -> A e. RR ) | 
						
							| 2 |  | 2itscp.b |  |-  ( ph -> B e. RR ) | 
						
							| 3 |  | 2itscp.x |  |-  ( ph -> X e. RR ) | 
						
							| 4 |  | 2itscp.y |  |-  ( ph -> Y e. RR ) | 
						
							| 5 |  | 2itscp.d |  |-  D = ( X - A ) | 
						
							| 6 |  | 2itscp.e |  |-  E = ( B - Y ) | 
						
							| 7 |  | 2itscp.c |  |-  C = ( ( D x. B ) + ( E x. A ) ) | 
						
							| 8 |  | 2itscp.r |  |-  ( ph -> R e. RR ) | 
						
							| 9 |  | 2itscplem3.q |  |-  Q = ( ( E ^ 2 ) + ( D ^ 2 ) ) | 
						
							| 10 |  | 2itscplem3.s |  |-  S = ( ( ( R ^ 2 ) x. Q ) - ( C ^ 2 ) ) | 
						
							| 11 | 10 | a1i |  |-  ( ph -> S = ( ( ( R ^ 2 ) x. Q ) - ( C ^ 2 ) ) ) | 
						
							| 12 | 9 | a1i |  |-  ( ph -> Q = ( ( E ^ 2 ) + ( D ^ 2 ) ) ) | 
						
							| 13 | 12 | oveq2d |  |-  ( ph -> ( ( R ^ 2 ) x. Q ) = ( ( R ^ 2 ) x. ( ( E ^ 2 ) + ( D ^ 2 ) ) ) ) | 
						
							| 14 | 8 | recnd |  |-  ( ph -> R e. CC ) | 
						
							| 15 | 14 | sqcld |  |-  ( ph -> ( R ^ 2 ) e. CC ) | 
						
							| 16 | 2 | recnd |  |-  ( ph -> B e. CC ) | 
						
							| 17 | 4 | recnd |  |-  ( ph -> Y e. CC ) | 
						
							| 18 | 16 17 | subcld |  |-  ( ph -> ( B - Y ) e. CC ) | 
						
							| 19 | 6 18 | eqeltrid |  |-  ( ph -> E e. CC ) | 
						
							| 20 | 19 | sqcld |  |-  ( ph -> ( E ^ 2 ) e. CC ) | 
						
							| 21 | 3 | recnd |  |-  ( ph -> X e. CC ) | 
						
							| 22 | 1 | recnd |  |-  ( ph -> A e. CC ) | 
						
							| 23 | 21 22 | subcld |  |-  ( ph -> ( X - A ) e. CC ) | 
						
							| 24 | 5 23 | eqeltrid |  |-  ( ph -> D e. CC ) | 
						
							| 25 | 24 | sqcld |  |-  ( ph -> ( D ^ 2 ) e. CC ) | 
						
							| 26 | 20 25 | addcld |  |-  ( ph -> ( ( E ^ 2 ) + ( D ^ 2 ) ) e. CC ) | 
						
							| 27 | 15 26 | mulcomd |  |-  ( ph -> ( ( R ^ 2 ) x. ( ( E ^ 2 ) + ( D ^ 2 ) ) ) = ( ( ( E ^ 2 ) + ( D ^ 2 ) ) x. ( R ^ 2 ) ) ) | 
						
							| 28 | 20 25 15 | adddird |  |-  ( ph -> ( ( ( E ^ 2 ) + ( D ^ 2 ) ) x. ( R ^ 2 ) ) = ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) ) | 
						
							| 29 | 13 27 28 | 3eqtrd |  |-  ( ph -> ( ( R ^ 2 ) x. Q ) = ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) ) | 
						
							| 30 | 1 2 3 4 5 6 7 | 2itscplem2 |  |-  ( ph -> ( C ^ 2 ) = ( ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) + ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) ) | 
						
							| 31 | 29 30 | oveq12d |  |-  ( ph -> ( ( ( R ^ 2 ) x. Q ) - ( C ^ 2 ) ) = ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) + ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) ) ) | 
						
							| 32 | 20 15 | mulcld |  |-  ( ph -> ( ( E ^ 2 ) x. ( R ^ 2 ) ) e. CC ) | 
						
							| 33 | 25 15 | mulcld |  |-  ( ph -> ( ( D ^ 2 ) x. ( R ^ 2 ) ) e. CC ) | 
						
							| 34 | 32 33 | addcld |  |-  ( ph -> ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) e. CC ) | 
						
							| 35 | 16 | sqcld |  |-  ( ph -> ( B ^ 2 ) e. CC ) | 
						
							| 36 | 25 35 | mulcld |  |-  ( ph -> ( ( D ^ 2 ) x. ( B ^ 2 ) ) e. CC ) | 
						
							| 37 |  | 2cnd |  |-  ( ph -> 2 e. CC ) | 
						
							| 38 | 24 22 | mulcld |  |-  ( ph -> ( D x. A ) e. CC ) | 
						
							| 39 | 19 16 | mulcld |  |-  ( ph -> ( E x. B ) e. CC ) | 
						
							| 40 | 38 39 | mulcld |  |-  ( ph -> ( ( D x. A ) x. ( E x. B ) ) e. CC ) | 
						
							| 41 | 37 40 | mulcld |  |-  ( ph -> ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) e. CC ) | 
						
							| 42 | 34 36 41 | subsub4d |  |-  ( ph -> ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) = ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) ) | 
						
							| 43 | 42 | eqcomd |  |-  ( ph -> ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) = ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) | 
						
							| 44 | 43 | oveq1d |  |-  ( ph -> ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) = ( ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) ) | 
						
							| 45 | 34 36 | subcld |  |-  ( ph -> ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) e. CC ) | 
						
							| 46 | 22 | sqcld |  |-  ( ph -> ( A ^ 2 ) e. CC ) | 
						
							| 47 | 20 46 | mulcld |  |-  ( ph -> ( ( E ^ 2 ) x. ( A ^ 2 ) ) e. CC ) | 
						
							| 48 | 45 41 47 | sub32d |  |-  ( ph -> ( ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) = ( ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) | 
						
							| 49 | 44 48 | eqtrd |  |-  ( ph -> ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) = ( ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) | 
						
							| 50 | 36 41 | addcld |  |-  ( ph -> ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) e. CC ) | 
						
							| 51 | 34 50 47 | subsub4d |  |-  ( ph -> ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) = ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) + ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) ) ) | 
						
							| 52 | 32 33 36 | addsubassd |  |-  ( ph -> ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) = ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( ( D ^ 2 ) x. ( R ^ 2 ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) ) ) | 
						
							| 53 | 25 15 35 | subdid |  |-  ( ph -> ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) = ( ( ( D ^ 2 ) x. ( R ^ 2 ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) ) | 
						
							| 54 | 53 | eqcomd |  |-  ( ph -> ( ( ( D ^ 2 ) x. ( R ^ 2 ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) = ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) | 
						
							| 55 | 54 | oveq2d |  |-  ( ph -> ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( ( D ^ 2 ) x. ( R ^ 2 ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) ) = ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) ) | 
						
							| 56 | 52 55 | eqtrd |  |-  ( ph -> ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) = ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) ) | 
						
							| 57 | 56 | oveq1d |  |-  ( ph -> ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) = ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) ) | 
						
							| 58 | 15 35 | subcld |  |-  ( ph -> ( ( R ^ 2 ) - ( B ^ 2 ) ) e. CC ) | 
						
							| 59 | 25 58 | mulcld |  |-  ( ph -> ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) e. CC ) | 
						
							| 60 | 32 59 47 | addsubd |  |-  ( ph -> ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) = ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) ) | 
						
							| 61 | 20 15 46 | subdid |  |-  ( ph -> ( ( E ^ 2 ) x. ( ( R ^ 2 ) - ( A ^ 2 ) ) ) = ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) ) | 
						
							| 62 | 61 | eqcomd |  |-  ( ph -> ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) = ( ( E ^ 2 ) x. ( ( R ^ 2 ) - ( A ^ 2 ) ) ) ) | 
						
							| 63 | 62 | oveq1d |  |-  ( ph -> ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) = ( ( ( E ^ 2 ) x. ( ( R ^ 2 ) - ( A ^ 2 ) ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) ) | 
						
							| 64 | 57 60 63 | 3eqtrd |  |-  ( ph -> ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) = ( ( ( E ^ 2 ) x. ( ( R ^ 2 ) - ( A ^ 2 ) ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) ) | 
						
							| 65 | 64 | oveq1d |  |-  ( ph -> ( ( ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( D ^ 2 ) x. ( B ^ 2 ) ) ) - ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) = ( ( ( ( E ^ 2 ) x. ( ( R ^ 2 ) - ( A ^ 2 ) ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) | 
						
							| 66 | 49 51 65 | 3eqtr3d |  |-  ( ph -> ( ( ( ( E ^ 2 ) x. ( R ^ 2 ) ) + ( ( D ^ 2 ) x. ( R ^ 2 ) ) ) - ( ( ( ( D ^ 2 ) x. ( B ^ 2 ) ) + ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) + ( ( E ^ 2 ) x. ( A ^ 2 ) ) ) ) = ( ( ( ( E ^ 2 ) x. ( ( R ^ 2 ) - ( A ^ 2 ) ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) | 
						
							| 67 | 11 31 66 | 3eqtrd |  |-  ( ph -> S = ( ( ( ( E ^ 2 ) x. ( ( R ^ 2 ) - ( A ^ 2 ) ) ) + ( ( D ^ 2 ) x. ( ( R ^ 2 ) - ( B ^ 2 ) ) ) ) - ( 2 x. ( ( D x. A ) x. ( E x. B ) ) ) ) ) |