Polygons & 3D Shapes Vocabulary Flashcards

This is a collection of flashcards summarizing key vocabulary and definitions related to polygons and 3D shapes discussed in Chapter 16 and Chapter 17 of the lecture notes.

Polygon

A closed 2-dimensional shape made of straight line segments that meet only at their endpoints.

Concave

A polygon with at least one interior angle greater than 180°.

Convex

A polygon where all interior angles are less than 180°.

Equilateral

A polygon where all sides are of the same length.

Equiangular

A polygon where all interior angles are the same measure.

Regular polygon

A polygon that is both equilateral and equiangular.

Equilateral triangle

A triangle with all sides equal and all angles measuring 60°.

Isosceles triangle

A triangle with at least two sides equal and base angles equal.

Scalene triangle

A triangle with all sides of different lengths.

Right triangle

A triangle with one angle measuring 90°.

Acute triangle

A triangle with all angles measuring less than 90°.

Obtuse triangle

A triangle with one angle measuring greater than 90°.

Parallelogram

A quadrilateral with opposite sides parallel and equal in length.

Rectangle

A parallelogram with all angles measuring 90°.

Rhombus

A parallelogram with all sides equal.

Square

A rectangle with all sides equal.

Trapezoid

A quadrilateral with exactly one pair of parallel sides.

Kite

A quadrilateral with two pairs of adjacent equal sides.

Diagonals in Polygons

The number of diagonals in an n-sided polygon is given by the formula n(n-3)/2.

Interior Angles

The sum of interior angles of any polygon with n sides is (n - 2) × 180°.

Exterior Angles

The sum of exterior angles of any polygon is always 360°.

Polyhedron

A 3D shape with flat polygonal faces, straight edges, and vertices.

Face

A flat polygonal surface on a polyhedron.

Edge

A line segment where two faces of a polyhedron meet.

Vertex / Vertices

A point where three or more edges of a polyhedron meet.

Apex

The top point of a pyramid.

Base

The bottom face of a prism or pyramid.

Prism

A polyhedron with two parallel congruent bases and lateral faces that are parallelograms.

Pyramid

A polyhedron with one base and triangular lateral faces meeting at an apex.

Platonic Solids

The five types of regular polyhedra with congruent faces: tetrahedron, cube, octahedron, dodecahedron, and icosahedron.

Net

A 2D pattern that can be folded to form a 3D polyhedron.

Euler’s formula

For convex polyhedra, V - E + F = 2, where V is vertices, E is edges, and F is faces.