A set of polygons contains a square, a rectangle, a rhombus and a trapezoid. If one polygon is chosen at random, what is the probability that the polygon has all sides congruent and all right angles?
A square and rhombus are the only polygons with congruent sides.
A square and rectangle are the only polygons with all right angles.
And thus, we want to know which polygon has all sides congruent, as well as all right angles. As shown above, only a square does.
Therefore, there is a 1/4 chance in choosing a polygon that has all sides congruent and all right angles.