Figure abcd is a square. prove bd ≅ ac. statements reasons 1. abcd is a square 1. given 2. ∠dab, ∠abc, ∠bcd, and ∠cda are right angles 2. definition of a square 3. ∠dab ≅ ∠abc ≅ ∠bcd ≅ ∠cda 3. right angles are congruent 4. ab ≅ bc ≅ cd ≅ da 4. ? 5. △bad ≅ △abc 5. sas 6. bd ≅ ac 6. cpctc what is the missing reason in the proof? all sides of a square are congruent all right angles measure 90° definition of diagonal definition of perpendicular