Question

Which of the following is always a rhombus: Parallelogram, Trapezoid, Rectangle, or Square?

Answer 1

A square is always a rhombus, whereas each of a parallelogram, a trapezoid, and a rectangle do not have to be.

Explanation:

A rhombus is a quadrilateral with all four sides being of equal length.
To see which of the given shapes fall into this category, let's look at their definitions.

A parallelogram is a quadrilateral with two pairs of parallel sides.
A trapezoid is a quadrilateral with at least one pair of parallel sides.
A rectangle is a quadrilateral with four right angles.
A square is a quadrilateral with four right angles and equal side lengths.

Looking at the definitions, a square is already guaranteed to be a rhombus. Here are examples of each of the other shapes which are not rhombuses.