Given: PQ | P’Q’
Prove: (m PQ) (m P’Q’) = -1
1. m PQ = y2-y1/x2-x1 = [spade]/c-a
[spade] =
2. m P’Q’ = y2-y1/x2-x1 = c-a/[heart]
[heart] =
3. m P’Q’ = c-a/-d-(-b) = c-a/[spade]
[spade] =