Which of the following statements is not always true?

A.
In a rhombus, the diagonals bisect opposite angles.
B.
In a rhombus, the diagonals are perpendicular.
C.
In a rhombus, the diagonals are congruent.
D.
In a rhombus, all four sides are congruent.

I think the answer is A. :-)

To determine which statement is not always true, let's analyze each statement:

A. In a rhombus, the diagonals bisect opposite angles.
This statement is always true in a rhombus. The diagonals of a rhombus bisect the opposite angles, forming four congruent triangles.

B. In a rhombus, the diagonals are perpendicular.
This statement is always true in a rhombus. The diagonals of a rhombus intersect at right angles, making them perpendicular.

C. In a rhombus, the diagonals are congruent.
This statement is always true in a rhombus. The diagonals of a rhombus are of equal length, making them congruent.

D. In a rhombus, all four sides are congruent.
This statement is always true in a rhombus. All four sides of a rhombus are of equal length, making them congruent.

Therefore, the statement that is not always true is A. In a rhombus, the diagonals bisect opposite angles.

To determine which of the given statements is not always true for a rhombus, let's first review the properties of a rhombus.

A rhombus is a parallelogram with four congruent sides. It has the following properties:

1. Opposite angles of a rhombus are congruent.
2. Diagonals of a rhombus bisect each other.
3. Diagonals of a rhombus are perpendicular.
4. Diagonals of a rhombus bisect opposite angles.
5. All four sides of a rhombus are congruent.

Now, let's examine each statement to determine if it is always true for a rhombus:

A. "In a rhombus, the diagonals bisect opposite angles."
This statement is actually always true for a rhombus. According to property 4, the diagonals of a rhombus bisect opposite angles. Therefore, statement A is not the correct answer.

B. "In a rhombus, the diagonals are perpendicular."
This statement is always true for a rhombus, according to property 3. The diagonals of a rhombus are always perpendicular to each other.

C. "In a rhombus, the diagonals are congruent."
This statement is always true for a rhombus, according to property 2. The diagonals of a rhombus always bisect each other, meaning they divide each other into two congruent segments.

D. "In a rhombus, all four sides are congruent."
This statement is always true for a rhombus, according to property 5. All four sides of a rhombus are congruent.

So, after evaluating each statement, the correct answer is not statement A but rather option D. In a rhombus, all four sides are always congruent, while the diagonals bisect opposite angles, are perpendicular, and are congruent.

C is true only if the rhombus is a square

B is the right answer.