Given: segment ac is perpendicular to segment bd prove: δacb ~ δecd reflect δecd over segment ac. this establishes that then, this establishes that ∠e'd'c' ≅ ∠abc. therefore, δacb ~ δecd by the aa similarity postulate. a.∠abc ≅ ∠e'd'c'; translate point e' to point ab.∠acb ≅ ∠e'c'd'; translate point e' to point b c.∠acb ≅ ∠e'c'd'; translate point d' to point bd.∠abc ≅ ∠e'd'c'; translate point d' to point a