Geometry Flashcards for Grades 3-4

These flashcards cover key geometry vocabulary and definitions related to angles, lines, and shapes.

Obtuse Angle

An angle greater than 90 degrees but less than 180 degrees.

Acute Angle

An angle that is less than 90 degrees.

Right Angle

An angle that measures exactly 90 degrees.

Line Segment

A part of a line that has two endpoints.

Ray

A part of a line that starts at one point and extends infinitely in one direction.

Perpendicular Lines

Lines that intersect at a right angle.

Parallel Lines

Lines in a plane that never meet and are always the same distance apart.

Quadrilateral

A polygon that has four sides.

Rhombus

A quadrilateral with all four sides of equal length.

Rectangle

A quadrilateral with four right angles.

Square

A quadrilateral with four equal sides and four right angles.

Parallelogram

A quadrilateral with opposite sides that are parallel and equal.

Trapezoid

A quadrilateral that has at least one pair of parallel sides.

Circle

A round shape with no corners or edges, defined by a center point and a radius.

Triangle

A polygon with three sides.

Pentagon

A polygon with five sides.