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 A B C A ih B + C = A ih B + A ih C

Proof

Step Hyp Ref Expression
1 ax-his2 B C A B + C ih A = B ih A + C ih A
2 1 fveq2d B C A B + C ih A = B ih A + C ih A
3 hicl B A B ih A
4 hicl C A C ih A
5 cjadd B ih A C ih A B ih A + C ih A = B ih A + C ih A
6 3 4 5 syl2an B A C A B ih A + C ih A = B ih A + C ih A
7 6 3impdir B C A B ih A + C ih A = B ih A + C ih A
8 2 7 eqtrd B C A B + C ih A = B ih A + C ih A
9 8 3comr A B C B + C ih A = B ih A + C ih A
10 hvaddcl B C B + C
11 ax-his1 A B + C A ih B + C = B + C ih A
12 10 11 sylan2 A B C A ih B + C = B + C ih A
13 12 3impb A B C A ih B + C = B + C ih A
14 ax-his1 A B A ih B = B ih A
15 14 3adant3 A B C A ih B = B ih A
16 ax-his1 A C A ih C = C ih A
17 16 3adant2 A B C A ih C = C ih A
18 15 17 oveq12d A B C A ih B + A ih C = B ih A + C ih A
19 9 13 18 3eqtr4d A B C A ih B + C = A ih B + A ih C