Lines, Angles, and Curves: 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."

a straight line that is terminated by a secondary line at each end, resembling the letter H

"A balbis has ends."

"A balbis is a single line segment that ends in two perpendicular lines resembling a capital H without the crossbar."

a portion of a straight line that is defined by two distinct endpoints

"A line segment has two endpoints."

"A line segment is part of a straight line bounded by two distinct endpoints."

a line that crosses a curve at least at two distinct points

"A secant intersects two points."

"A secant is a line that intersects a curve or circle at two distinct points."

a pair of adjacent angles formed by two intersecting lines, which add up to 180 degrees

"A linear pair forms a line."

"A linear pair is a pair of adjacent angles formed when two lines intersect and their measures sum to one hundred eighty degrees."

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."

an angle that measures either less or more that 90 degrees

"An oblique angle is not right."

"An oblique angle is any angle that is not a right angle or a straight angle."

an angle that measures greater than 180 degrees but less than 360 degrees

"The angle is a reflex angle."

"A reflex angle is an angle greater than 180 degrees but less than 360 degrees."

a complete revolution or turn around a fixed point or axis, covering a 360-degree angle

"A full rotation is 360 degrees."

"A full rotation is a complete turn of three hundred sixty degrees around a point."

an angle measured counterclockwise from the initial side of a reference angle in standard position, usually expressed in degrees or radians

"Positive angles rotate counterclockwise."

"A positive angle is measured counterclockwise from the initial side to the terminal side."

an angle measured clockwise from the initial side of a reference angle in standard position, usually expressed in degrees or radians

"Negative angles rotate clockwise."

"A negative angle is measured clockwise from the initial side to the terminal side."

two angles that share a common vertex and a common side, but do not overlap, and are not in a straight line

"Adjacent angles share a vertex."

"Adjacent angles share a common vertex and a common side but do not overlap."

the measure of the tilt between two lines or surfaces in two-dimensional space, typically given in degrees or radians

"The plane angle is measured."

"A plane angle is the figure formed by two rays that share a common endpoint in a flat plane."

a shape, line or surface that is hollow and is rounded inward

"The concavity curves inward."

"Concavity describes the inward curvature of a shape like the inside of a cave or a bowl."

(geometry) a shape formed when a circular cone is intersected by a plane

"Conic sections include circles and ellipses."

"Conic sections are the curves formed by intersecting a plane with a double cone producing circles ellipses parabolas and hyperbolas."

(geometry) a closed plane curve that has two focal points

"An ellipse is oval."

"The orbit of a planet around the sun is not a perfect circle but rather an ellipse with the sun at one focus."

(geometry) a symmetrical open curve that is similar to the path of an object thrown into the air passes till it falls back to earth

"The parabola is a curve."

"The ball flew in a perfect parabola before landing exactly where the player had aimed it."

a geometric curve formed by the intersection of a plane with two cones, resulting in two symmetrical branches

"The hyperbola has two separate curves."

"A hyperbola is a conic section formed by slicing a double cone at a steep angle"

a continuous curve that does not intersect itself, and can be traced without lifting the pen or pencil from the paper

"A simple curve does not cross itself."

"A simple curve does not cross itself and can be open or closed."

a curve that intersects itself, or has overlapping segments, requiring the pen or pencil to be lifted from the paper while tracing it

"A non-simple curve crosses itself."

"A non simple curve crosses itself at least once like a figure eight or a pretzel shape."

a curve that does not intersect itself and has distinct endpoints, meaning it does not form a closed shape or loop

"An open curve has endpoints."

"An open curve has two distinct endpoints and does not form a closed loop."

a curve that begins and ends at the same point, forming a closed loop

"A closed curve has no endpoints."

"A closed curve has no endpoints and forms a continuous loop like a circle or an ellipse."