Geometry Study Cards

Enhance Your Learning with Geometry Flash Cards for quick learning



Point

A location in space with no size or shape.

Line

A straight path that extends infinitely in both directions.

Line Segment

A part of a line with two endpoints.

Ray

A part of a line with one endpoint that extends infinitely in one direction.

Parallel Lines

Lines in the same plane that never intersect.

Perpendicular Lines

Lines that intersect at a 90-degree angle.

Intersecting Lines

Lines that cross each other at a point.

Acute Angle

An angle that measures less than 90 degrees.

Right Angle

An angle that measures exactly 90 degrees.

Obtuse Angle

An angle that measures more than 90 degrees but less than 180 degrees.

Straight Angle

An angle that measures exactly 180 degrees.

Adjacent Angles

Two angles that share a common vertex and side, but have no common interior points.

Vertical Angles

Two nonadjacent angles formed by intersecting lines.

Complementary Angles

Two angles whose measures add up to 90 degrees.

Supplementary Angles

Two angles whose measures add up to 180 degrees.

Polygon

A closed figure formed by three or more line segments.

Triangle

A polygon with three sides.

Equilateral Triangle

A triangle with three congruent sides.

Isosceles Triangle

A triangle with at least two congruent sides.

Scalene Triangle

A triangle with no congruent sides.

Right Triangle

A triangle with one right angle.

Obtuse Triangle

A triangle with one obtuse angle.

Acute Triangle

A triangle with three acute angles.

Quadrilateral

A polygon with four sides.

Rectangle

A quadrilateral with four right angles.

Square

A quadrilateral with four congruent sides and four right angles.

Rhombus

A quadrilateral with four congruent sides.

Parallelogram

A quadrilateral with opposite sides that are parallel and congruent.

Trapezoid

A quadrilateral with one pair of parallel sides.

Circle

A round shape with all points equidistant from the center.

Radius

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

Diameter

A line segment that passes through the center of a circle and has endpoints on the circle.

Circumference

The distance around a circle.

Area

The measure of the amount of space inside a shape.

Perimeter

The distance around the outside of a shape.

Volume

The measure of the amount of space inside a three-dimensional shape.

Surface Area

The sum of the areas of all the faces of a three-dimensional shape.

Coordinate Plane

A plane formed by two perpendicular number lines called axes.

Ordered Pair

A pair of numbers used to locate a point on a coordinate plane.

Translation

A transformation that slides a figure from one position to another without changing its shape or size.

Reflection

A transformation that flips a figure over a line, creating a mirror image.

Rotation

A transformation that turns a figure around a fixed point called the center of rotation.

Dilation

A transformation that changes the size of a figure, but not its shape.

Proof

A logical argument that shows a statement is true.

Theorem

A statement that can be proven true using previously proven statements and definitions.

Hypotenuse

The side opposite the right angle in a right triangle.

Sine

In a right triangle, the ratio of the length of the side opposite an acute angle to the length of the hypotenuse.

Cosine

In a right triangle, the ratio of the length of the side adjacent to an acute angle to the length of the hypotenuse.

Tangent

In a right triangle, the ratio of the length of the side opposite an acute angle to the length of the side adjacent to the acute angle.

Bisect

To divide into two congruent parts.

Perpendicular Bisector

A line, segment, or ray that is perpendicular to a segment at its midpoint.

Angle Bisector

A ray that divides an angle into two congruent angles.

Compass

A tool used to draw circles and arcs.

Straightedge

A tool used to draw straight lines.

Pythagorean Theorem

In a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides.

Area of a Triangle

The measure of the amount of space inside a triangle.

Area of a Rectangle

The measure of the amount of space inside a rectangle.

Area of a Square

The measure of the amount of space inside a square.

Area of a Circle

The measure of the amount of space inside a circle.

Volume of a Prism

The measure of the amount of space inside a prism.

Volume of a Cylinder

The measure of the amount of space inside a cylinder.

Surface Area of a Prism

The sum of the areas of all the faces of a prism.

Surface Area of a Cylinder

The sum of the areas of all the faces of a cylinder.