Metamath Proof Explorer


Theorem his2sub2

Description: Distributive law for inner product of vector subtraction. (Contributed by NM, 13-Feb-2006) (New usage is discouraged.)

Ref Expression
Assertion his2sub2 ABCAihB-C=AihBAihC

Proof

Step Hyp Ref Expression
1 his2sub BCAB-CihA=BihACihA
2 1 fveq2d BCAB-CihA=BihACihA
3 hicl BABihA
4 hicl CACihA
5 cjsub BihACihABihACihA=BihACihA
6 3 4 5 syl2an BACABihACihA=BihACihA
7 6 3impdir BCABihACihA=BihACihA
8 2 7 eqtrd BCAB-CihA=BihACihA
9 8 3comr ABCB-CihA=BihACihA
10 hvsubcl 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 ABCAihBAihC=BihACihA
19 9 13 18 3eqtr4d ABCAihB-C=AihBAihC