5th Grade Geometry Terms

A polygon with three sides is called a triangle.

A right triangle is defined as a triangle that has one angle measuring 90 degrees. Therefore, it is true that a right triangle has one 90 degree angle.

A polygon with four sides is called a quadrilateral.

An isosceles triangle is a triangle that has two sides of equal length. This means that two of its sides are the same length, while the third side may be a different length. Therefore, the statement that an isosceles triangle has two sides that are the same length is true.

A polygon with eight sides is called an octagon.

A polygon with five sides is called a pentagon.

A scalene triangle is a type of triangle that has no equal sides. This means that all three sides of a scalene triangle have different lengths. Therefore, the correct answer is true.

A polygon with 6 sides is called a hexagon. The prefix "hex-" means six in Greek, so a hexagon is a polygon with six sides.

A square is a parallelogram with all sides the same length and four right angles. It is the only shape among the options that satisfies these conditions. A trapezoid has at least one pair of parallel sides but does not have all sides the same length or four right angles. A rectangle has four right angles but does not have all sides the same length. A parallelogram has opposite sides parallel but does not have all sides the same length or four right angles. A rhombus has all sides the same length but does not have four right angles. Therefore, the correct answer is square.

An obtuse angle is not made up of three obtuse angles. An obtuse angle is an angle that measures more than 90 degrees but less than 180 degrees. It is a single angle and cannot be composed of multiple angles. Therefore, the statement is false.

An acute triangle is a triangle that contains three acute angles, meaning all three angles are less than 90 degrees. Therefore, the statement that an acute triangle contains only one acute angle is incorrect.

A rhombus is a parallelogram with all four sides equal in length, but it does not have any right angles. It is a special type of parallelogram that has opposite sides parallel and opposite angles equal. Unlike a rectangle or a square, a rhombus does not have any right angles. Therefore, a rhombus is the correct answer to this question.

A trapezoid is a quadrilateral with only one pair of parallel sides. It can be made by using one quadrilateral and two triangles. A rectangle has two pairs of parallel sides, a rhombus has all sides equal in length, a parallelogram has opposite sides parallel and equal in length, and a square has all sides equal in length and all angles equal to 90 degrees. Therefore, the correct answer is trapezoid.

An equilateral triangle is defined as a triangle with all three sides of equal length. This also means that all three angles of an equilateral triangle are equal, each measuring 60 degrees.

A parallelogram is a quadrilateral with two pairs of parallel sides. It is a shape where opposite sides are parallel and equal in length. This makes it different from a rectangle, square, rhombus, and trapezoid, as they do not necessarily have two pairs of parallel sides. Therefore, a parallelogram is the correct answer for a quadrilateral with two parallel sides.

A rectangle is a parallelogram with four right angles. It is a quadrilateral with opposite sides that are equal in length and parallel to each other. The fact that it has four right angles distinguishes it from other parallelograms, such as the rhombus and trapezoid, which do not necessarily have right angles. A square is a special type of rectangle where all sides are equal in length. Therefore, the correct answer is rectangle.