Which biconditional statement is true?
a. a shape is a rectangle if and only if the shape has exactly four sides and four right angles.
b. a shape is a trapezoid if and only if the shape has a pair of parallel sides.
c. a shape is a triangle if and only if the shape has three sides and three acute angles.
d. a shape is a square if and only if the shape has exactly four congruent side

Answer;

A .a shape is a rectangle if and only if the shape has exactly four sides and four right angles.

Explanation;

-A rectangle is a 4-sided flat shape with straight sides where all interior angles are right angles (90°). Also opposite sides are parallel and of equal length. Example: A square is a special type of rectangle, here all the four sides are equal.

Therefore; the characteristics of a rectangle include;

-All the properties of a parallelogram apply (the ones that matter here are parallel sides, opposite sides are congruent, and diagonals bisect each other).

-All angles are right angles by definition.

-The diagonals are congruent.