Which of the following statements is not true?

(A) A quadrilateral has four sides.

(B) The sum of the angles in a triangle is $180^{\circ}$.

(C) A rectangle has four $90^{\circ}$ angles.

(D) A triangle can have two $90^{\circ}$ angles.

(E) A rectangle is a quadrilateral.

## Grade 8

## Part B: Each correct answer is worth 6.
Which of the following statements is not true?

(A) A quadrilateral has four sides.

(B) The sum of the angles in a triangle is $180 r$.

(C) A rectangle has four 90r angles.

(D) A triangle can have two 90r angles.

(E) A rectangle is a quadrilateral.

## Solution

A quadrilateral has four sides, by definition.

The sum of the angles in a triangle is $180^{\circ}$.

A rectangle has four $90^{\circ}$ angles, by definition.

A rectangle is a quadrilateral, since it has four sides.

However, a triangle cannot have two $90^{\circ}$, since its three angles add to $180^{\circ}$, and its third angle cannot be $0^{\circ}$.

ANSWER: (D)

## Part B