| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mirval.p |  |-  P = ( Base ` G ) | 
						
							| 2 |  | mirval.d |  |-  .- = ( dist ` G ) | 
						
							| 3 |  | mirval.i |  |-  I = ( Itv ` G ) | 
						
							| 4 |  | mirval.l |  |-  L = ( LineG ` G ) | 
						
							| 5 |  | mirval.s |  |-  S = ( pInvG ` G ) | 
						
							| 6 |  | mirval.g |  |-  ( ph -> G e. TarskiG ) | 
						
							| 7 |  | mirtrcgr.e |  |-  .~ = ( cgrG ` G ) | 
						
							| 8 |  | mirtrcgr.m |  |-  M = ( S ` B ) | 
						
							| 9 |  | mirtrcgr.n |  |-  N = ( S ` Y ) | 
						
							| 10 |  | mirtrcgr.a |  |-  ( ph -> A e. P ) | 
						
							| 11 |  | mirtrcgr.b |  |-  ( ph -> B e. P ) | 
						
							| 12 |  | mirtrcgr.x |  |-  ( ph -> X e. P ) | 
						
							| 13 |  | mirtrcgr.y |  |-  ( ph -> Y e. P ) | 
						
							| 14 |  | mircgrextend.1 |  |-  ( ph -> ( A .- B ) = ( X .- Y ) ) | 
						
							| 15 | 1 2 3 4 5 6 11 8 10 | mircl |  |-  ( ph -> ( M ` A ) e. P ) | 
						
							| 16 | 1 2 3 4 5 6 13 9 12 | mircl |  |-  ( ph -> ( N ` X ) e. P ) | 
						
							| 17 | 1 2 3 4 5 6 11 8 10 | mirbtwn |  |-  ( ph -> B e. ( ( M ` A ) I A ) ) | 
						
							| 18 | 1 2 3 6 15 11 10 17 | tgbtwncom |  |-  ( ph -> B e. ( A I ( M ` A ) ) ) | 
						
							| 19 | 1 2 3 4 5 6 13 9 12 | mirbtwn |  |-  ( ph -> Y e. ( ( N ` X ) I X ) ) | 
						
							| 20 | 1 2 3 6 16 13 12 19 | tgbtwncom |  |-  ( ph -> Y e. ( X I ( N ` X ) ) ) | 
						
							| 21 | 1 2 3 6 10 11 12 13 14 | tgcgrcomlr |  |-  ( ph -> ( B .- A ) = ( Y .- X ) ) | 
						
							| 22 | 1 2 3 4 5 6 11 8 10 | mircgr |  |-  ( ph -> ( B .- ( M ` A ) ) = ( B .- A ) ) | 
						
							| 23 | 1 2 3 4 5 6 13 9 12 | mircgr |  |-  ( ph -> ( Y .- ( N ` X ) ) = ( Y .- X ) ) | 
						
							| 24 | 21 22 23 | 3eqtr4d |  |-  ( ph -> ( B .- ( M ` A ) ) = ( Y .- ( N ` X ) ) ) | 
						
							| 25 | 1 2 3 6 10 11 15 12 13 16 18 20 14 24 | tgcgrextend |  |-  ( ph -> ( A .- ( M ` A ) ) = ( X .- ( N ` X ) ) ) |