| Step | Hyp | Ref | Expression | 
						
							| 1 |  | hvmulcl |  |-  ( ( A e. CC /\ B e. ~H ) -> ( A .h B ) e. ~H ) | 
						
							| 2 |  | ax-his2 |  |-  ( ( ( A .h B ) e. ~H /\ C e. ~H /\ D e. ~H ) -> ( ( ( A .h B ) +h C ) .ih D ) = ( ( ( A .h B ) .ih D ) + ( C .ih D ) ) ) | 
						
							| 3 | 2 | 3expb |  |-  ( ( ( A .h B ) e. ~H /\ ( C e. ~H /\ D e. ~H ) ) -> ( ( ( A .h B ) +h C ) .ih D ) = ( ( ( A .h B ) .ih D ) + ( C .ih D ) ) ) | 
						
							| 4 | 1 3 | sylan |  |-  ( ( ( A e. CC /\ B e. ~H ) /\ ( C e. ~H /\ D e. ~H ) ) -> ( ( ( A .h B ) +h C ) .ih D ) = ( ( ( A .h B ) .ih D ) + ( C .ih D ) ) ) | 
						
							| 5 |  | ax-his3 |  |-  ( ( A e. CC /\ B e. ~H /\ D e. ~H ) -> ( ( A .h B ) .ih D ) = ( A x. ( B .ih D ) ) ) | 
						
							| 6 | 5 | 3expa |  |-  ( ( ( A e. CC /\ B e. ~H ) /\ D e. ~H ) -> ( ( A .h B ) .ih D ) = ( A x. ( B .ih D ) ) ) | 
						
							| 7 | 6 | adantrl |  |-  ( ( ( A e. CC /\ B e. ~H ) /\ ( C e. ~H /\ D e. ~H ) ) -> ( ( A .h B ) .ih D ) = ( A x. ( B .ih D ) ) ) | 
						
							| 8 | 7 | oveq1d |  |-  ( ( ( A e. CC /\ B e. ~H ) /\ ( C e. ~H /\ D e. ~H ) ) -> ( ( ( A .h B ) .ih D ) + ( C .ih D ) ) = ( ( A x. ( B .ih D ) ) + ( C .ih D ) ) ) | 
						
							| 9 | 4 8 | eqtrd |  |-  ( ( ( A e. CC /\ B e. ~H ) /\ ( C e. ~H /\ D e. ~H ) ) -> ( ( ( A .h B ) +h C ) .ih D ) = ( ( A x. ( B .ih D ) ) + ( C .ih D ) ) ) |