ACICD and AA BC ~ ACED Given: DC = -1 Prove: slope of AC x slope of Reasons Statements Given 1. ACICD AABC is similar to ACED Property of similar triangles 2. 3. slope of AC = AB BC ED CE Definition of slope CD = slope of AB EE Multiplying the slopes 4. slope of AC x slope of СЕ ED EC CE Substitution property of equality 5. slope of AĆ x slope of CD = - Simplifying the right side slope of AC x slope of CD = -1