Two-Dimensional Shapes: English Vocabulary List

(geometry) a flat shape with four right angles, especially one with opposing sides that are equal and parallel to each other

"The door is a rectangle."

"A rectangle has four sides and four right angles with opposite sides equal in length."

(geometry) a flat shape with four flat sides, two of which are parallel

"The trapezoid has one pair of parallel sides."

"A trapezoid is a quadrilateral with at least one set of parallel sides"

(geometry) any flat shape with four straight sides, the opposite sides of which are equal and parallel to each other

"A parallelogram is a four-sided shape with opposite sides that are parallel."

"A rectangle is a special type of parallelogram where all four angles are right angles."

(geometry) a flat shape with four equal sides in which opposite angles are equal

"A rhombus has four equal sides."

"A rhombus looks like a slanted square and has four equal sides with equal opposite angles."

(geometry) a flat shape consisting of three or more straight sides

"A polygon has sides."

"A polygon is a closed two-dimensional shape formed by straight line segments, such as a triangle or a square."

a flat geometric shape consisting of three straight sides and one right angle

"Right triangle has."

"A right triangle has one angle that measures exactly ninety degrees."

a triangle that does not have a right angle

"Oblique triangles have no right angle."

"An oblique triangle has no angle measuring ninety degrees so it is either acute or obtuse."

a type of triangle that has all three sides of different lengths

"A scalene triangle has no equal sides."

"A scalene triangle has three sides of different lengths and three different angles."

a type of triangle that has two sides of equal length and two angles of equal measure

"An isosceles triangle has two equal sides."

"An isosceles triangle has two sides of equal length and two equal angles opposite those sides."

a type of triangle with all three sides of equal length

"Draw equilateral triangle."

"We learned how to draw an equilateral triangle with three equal sides and angles."

a type of triangle in which all three angles are less than 90 degrees

"An acute-angled triangle has three angles."

"In geometry class, we learned that an acute-angled triangle has all three angles measuring less than 90 degrees."

a type of triangle that has one angle greater than 90 degrees

"Obtuse-angled triangles have one large angle."

"An obtuse angled triangle has one interior angle that measures more than ninety degrees."

any half of a circle

"The table was a semicircle."

"The architect designed a beautiful garden path in the shape of a semicircle around the fountain."