Talking about Geometry: English Vocabulary List

(geometry) a shape that consists of a line alternating its direction to left and right

"The path made a zigzag."

"The path through the mountains followed a steep zigzag, making the ascent challenging but rewarding."

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."

(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."

an angle that measures between 0 and 90 degrees, which is less than a right angle (90 degrees)

"The angle was acute."

"An acute angle measures less than ninety degrees, which makes it smaller than a right angle."

an angle that measures more than 90 degrees but less than 180 degrees

"The angle was obtuse."

"An obtuse angle measures more than ninety degrees but less than one hundred eighty degrees."

an angle measuring exactly 90 degrees

"The corner made a right angle."

"The corner of a square book forms a right angle that measures exactly ninety degrees."

an angle that measures exactly 180 degrees, which is the same as a straight line

"The line formed a straight angle."

"A straight angle measures exactly one hundred eighty degrees, forming a straight line."