In the figure above cd is the perpendicular bisector of ab. three students explained how they proved adc is congruent to bdcwho's explanation is incorrect? ?

All three explanations are correct.

Step-by-step explanation:

In the given triangles CD is perpendicular bisector of AB

So we have

AC= BC  ( C is on perpendicular bisector of AB and hence C is equidistant              from A and B)

∠ADC =∠BDC =90°                 ( CD ⊥ AB)

CD = CD   ( reflexive property)

AD = BD  (  CD is bisects AB)

We can use HL theorem or  SSS or SAS  to prove ΔADC≅ΔBDC

Hence all the three explanations are correct.

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