Diagonals AC and BD form right angles at point M in parallelogram ABCD. Prove ABCD is a rhombus. Statements Reasons1.ABCD is a parallelogram1.given2.∠AMB, ∠BMC, ∠CMD, and ∠DMA are right angles2.given3.∠AMB ≅ ∠BMC ≅ ∠CMD ≅ ∠DMA3.right angles are congruent4.AC bisects BD; BD bisects AC;4.diagonals of a parallelogram bisect each other5.AM ≅ MC, MB ≅ MD5.definition of a bisector6.?6.SAS congruency theorem7.AB ≅ BC ≅ CD ≅ DA7.CPCTC8.figure ABCD is a rhombus8.definition of a rhombus