FTCE General Knowledge Math Practice Test

What do all parallelograms have in common regarding their opposite sides?

1. They are always of equal length

2. They intersect at right angles

3. They can be of different lengths

4. They are always perpendicular

The correct answer is: They are always of equal length

All parallelograms share the characteristic that their opposite sides are always of equal length. This property stems from the definition of a parallelogram, which is a four-sided figure (quadrilateral) with opposite sides that are parallel. When two sides are parallel and opposite each other, they must be of equal length due to the properties of parallel lines and the consistent distance between them. By contrast, the other options do not apply universally to parallelograms. For instance, parallelograms do not necessarily intersect at right angles; that property specifically describes rectangles and squares. Moreover, although a parallelogram can have sides of different lengths, the key point is that each pair of opposite sides must be equal, which disallows this option as a defining characteristic. Lastly, while some parallelograms have perpendicular sides, this is only true for rectangles and squares; hence, being perpendicular is not a feature common to all parallelograms.