Metamath Proof Explorer


Theorem his7

Description: Distributive law for inner product. Lemma 3.1(S7) of Beran p. 95. (Contributed by NM, 31-Jul-1999) (New usage is discouraged.)

Ref Expression
Assertion his7 ABCAihB+C=AihB+AihC

Proof

Step Hyp Ref Expression
1 ax-his2 BCAB+CihA=BihA+CihA
2 1 fveq2d BCAB+CihA=BihA+CihA
3 hicl BABihA
4 hicl CACihA
5 cjadd BihACihABihA+CihA=BihA+CihA
6 3 4 5 syl2an BACABihA+CihA=BihA+CihA
7 6 3impdir BCABihA+CihA=BihA+CihA
8 2 7 eqtrd BCAB+CihA=BihA+CihA
9 8 3comr ABCB+CihA=BihA+CihA
10 hvaddcl BCB+C
11 ax-his1 AB+CAihB+C=B+CihA
12 10 11 sylan2 ABCAihB+C=B+CihA
13 12 3impb ABCAihB+C=B+CihA
14 ax-his1 ABAihB=BihA
15 14 3adant3 ABCAihB=BihA
16 ax-his1 ACAihC=CihA
17 16 3adant2 ABCAihC=CihA
18 15 17 oveq12d ABCAihB+AihC=BihA+CihA
19 9 13 18 3eqtr4d ABCAihB+C=AihB+AihC