FTCE Professional Education Practice Exam

Which of the following statements is true about parallelograms?

1. Diagonals are equal

2. Opposite angles are always 90 degrees

3. Opposite sides are congruent

4. All angles are acute

The correct answer is: Opposite sides are congruent

In a parallelogram, one of the fundamental properties is that opposite sides are congruent, meaning they are of equal length. This property helps to define the shape of a parallelogram and is crucial in establishing its characteristics in geometry. When dealing with the other statements, it can be clarified that while diagonals do bisect each other, they are not necessarily equal in length unless the parallelogram is a rectangle or a rhombus. Additionally, opposite angles in a general parallelogram are equal but can have varying measures—it is not true that they are always 90 degrees unless the shape is a rectangle. Lastly, while a parallelogram can have all acute angles, this is not a requirement; it can have obtuse angles as well, meaning not all angles in a parallelogram are necessarily acute. Thus, the statement regarding opposite sides being congruent is the definitive property that holds true for all parallelograms, making it the correct choice.