Geometrical Structures Vocabulary

Flashcards covering fundamental geometrical concepts including points, lines, angles, circles, and various polygons as described in the lecture notes.

Point

A location on a space.

Line

The product of a point moving along a path.

Straight line

The shortest distance between two points.

Horizontal line

A line drawn from left to right.

Vertical line

A line drawn from top to bottom.

Inclined line

A line that is diagonal.

Perpendicular line

Lines that form $90$-degree angles with each other.

Parallel lines

Lines side by side that never meet even if they are extended.

Curve line

A line that is not straight.

Arc

A connected section of the circumference of a circle.

Circle

A close figure bounded by one curved line, or the set of all points in a plane that are at a given distance from a fixed point called a center.

Angle

Formed by two intersecting lines.

Straight angle

$180$-degree angle.

Right angle

$90$-degree angle.

Acute angle

Less than $90$-degree angle.

Obtuse angle

More than $90$-degree angle.

Diameter

A straight line passing through the center.

Radius

A line segment from the center to any point of the circle.

Chord

A line segment whose endpoints lie on the circle.

Segment

A portion of a circle bounded by an arc and a chord.

Tangent

A straight line that intersects a circle at exactly one point.

Secant

A straight line passing through two points in the circle but not at the center.

Quadrant

A part of the circle bounded by two radii forming $90$ degrees. It is $\frac{1}{4}$ of the circle.

Sector

A part of a circle bounded by two radii and an arc.

Concentric

Two or more circles with a common center.

Eccentric

Circles inside a circle having a different center.

Polygon

A closed figure consisting of straight lines.

Regular Polygon

A polygon where all sides are equal.

Irregular Polygon

A polygon with unequal sides.

Triangle

A polygon with $3$ sides and angles.

Equilateral Triangle

A triangle where all sides are equal.

Isosceles Triangle

A triangle where $2$ sides are equal.

Right Triangle

A triangle where one angle is $90$ degrees.

Scalene Triangle

A triangle with no equal sides and angle.

Quadrilateral

A polygon with $4$ sides and angles.

Parallelogram

A quadrilateral with two pair of parallel sides.

Square

A figure with $4$ equal sides and angles that are $90$ degrees.

Rectangle

A figure with $2$ unequal parallel lines and angles that are $90$ degrees.

Rhombus

A figure with $4$ equal sides and angles that are not $90$ degrees.

Rhomboid

A parallelogram where the angles are not $90$ degrees.

Trapezoid

A figure with one pair of unequal parallel lines and angles that are not $90$ degrees.

Trapezium

A figure with unequal sides and no parallel lines.

Pentagon

A polygon with $5$ sides.

Hexagon

A polygon with $6$ sides.

Heptagon

A polygon with $7$ sides.

Octagon

A polygon with $8$ sides.

Nonagon

A polygon with $9$ sides.

Decagon

A polygon with $10$ sides.