20. Given: BC = CD, AB=BD Prove: ABCD A B C D First, show that BC = CD and BC + CD = BD. Then use to show (Blank) that and 2CD = BD. Divide to show that CD= SO (Blank 2) (Blank 3) ABCD. That means that ABCD. 21. Given: WY > YX W Blank 1 options addition subtraction substitution Blank 2. options .BC+CD BD CD+CD=BD Blank 3 options . BC . BD Prove: mZZWY > mzYWX Z (Blank 1) Y mZYWX because if one side of a triangle is Proof: Because WY > YX, mZWXY longer than another side, then the angle opposite the longer side has a the angle opposite the shorter side. But (Blank 2) because mZZWY mZWXY, by the Exterior Angle Theorem, (Blank 3) mZZWY > mZYWX by the Property. (Blank 4) Blank 1 options . > < Blank 2 options greater measure than measure that is less than Blank 3 options Blank 4 options Reflexive Symmetric