** See below** ;
AC is congruent to BD in parallelogram ABCD, as proven using a two-column proof based on triangle congruence and properties of parallelograms. ;
The proof shows that in parallelogram ABCD, the diagonals AC and BD are congruent by using the properties of congruence and congruent triangles. Specifically, it applies the Side-Angle-Side (SAS) postulate to demonstrate that the triangles formed by the diagonals and the sides of the parallelogram are congruent. Consequently, it concludes that AC ≈ BD through the principle of corresponding parts of congruent triangles being congruent (CPCTC).
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