Colors and Shapes - Lines, Angles, and Curves

Read this lesson to learn the names of some lines, angles, and curves in English, such as "ray", "acute angle" and "arc".

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Colors and Shapes
axis [noun]

the central point or line around which an object turns

Ex: The planet 's tilt on its axis causes the seasons .
axis [noun]

a straight line that defines the symmetry or structure of a figure or object

Ex: The designer marked the central axis of the building .
cross [noun]

a mark or an object formed by two short lines or pieces crossing each other

Ex: The flag of Switzerland features a white cross on a red background .
diagonal [noun]

a straight line connecting opposite corners of a flat shape at an angle

Ex: The diagonal of the pentagon intersected at the center .
zigzag [noun]

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

balbis [noun]

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

ray [noun]

a straight line that starts at a point and extends infinitely in one direction

Ex: A ray has a definite starting point but no end .

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

parallel [noun]

a pair of geometric figures, such as lines or planes, that do not meet or intersect, no matter how far they are extended

Ex: The parallel between the two roads is noticeable from above .

a line or structure that meets another at a right angle, creating a 90-degree intersection

Ex: The bridge 's beams formed perpendiculars where they met .
tangent [noun]

a straight line that touches a curve or surface at exactly one point, known as the point of tangency

Ex: In geometry class , we learned how to draw a tangent to a circle , ensuring it only touched the circle at a single point .
secant [noun]

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

Ex: In calculus , the secant is often used to define the derivative at a point on a curve .

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

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

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

Ex: When two lines intersected , they formed two acute angles and two obtuse angles .

an angle measuring exactly 90 degrees

Ex: The painter meticulously ensured that the lines on the canvas formed right angles to create a sense of balance in the composition .

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

an angle that measures either less or more that 90 degrees

Ex: A 45-degree angle is considered an oblique angle , falling between 0 and 90 degrees .

an angle that measures 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

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

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

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

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

Ex: Open the laptop screen to create a wide plane angle for better visibility .
arc [noun]

(geometry) a part of a circle, which is curved

Ex: In a pie chart , each section can be represented by an arc of the circle .
arc [noun]

a curved shape, or something shaped this way

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

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

crescent [noun]

a curved shape with narrow points at the ends that appears wider in the middle, like the shape of the moon in its first and last quarters

Ex: She watched the crescent slowly grow each night as the moon waxed towards fullness .
curl [noun]

something that resembles a spiral or coil

Ex: He noticed a delicate curl of smoke rising from the chimney of the cabin .
spiral [noun]

(geometry) a curved shape or design that gradually winds around a center or axis

Ex: The tornado formed a destructive spiral as it swept across the plains , leaving devastation in its wake .
ellipse [noun]

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

parabola [noun]

(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

Ex: Designers use parabolas to create efficient lighting fixtures .

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

Ex: The distance between a point on the hyperbola and its two foci is constant , defining its geometric properties .

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

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

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

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