Math Terms: Geometry

Translation (b)

A _________ of the plane is a transformation which shifts all the points in a plane figure, without altering the shape of the figure.

Composite

A figure that is made up of two or more basic figures is called __________.

Point-Slope Form

A form of writing a linear equation when you are given 2 points. y - y1 = m(x - x1).

Symmetry (a)

A line which divides an object into two mirror images is called a line of _________.

Rhombus

A parallelogram with four congruent sides.

Symmetry (b)

A plane which cuts a solid into two identical halves is called a plane of _____________.

Inscribed Polygon

A polygon whose vertices lie on a circle.

Regular Polygon

A polygon with congruent angles and congruent sides is called a ______ polygon.

Octagon

A polygon with eight sides.

Pentagon

A polygon with five sides.

Hexagon

A polygon with six sides.

Kite

A quadrilateral with two pairs of adjacent congruent sides.

Square

A rhombus with four right angles.

Apothem

A segment drawn from the center of a regular polygon perpendicular to the side of the polygon.

Circumscribed

A term for a geometric figure that encloses another geometric figure.

Rigid

A transformation is called _________ if it preserves the shape and size of an object.

Dilation

A transformation that increases or decreased the size of a figure according to the scale factor.

Equiangular Triangle

A triangle with all congruent angles.

Obtuse Triangle

A triangle with one angle that measures more than 90 degrees.

Composite Figure

An irregular shape that can be split into familiar shapes such as rectangles, triangles, and circles in order to find the area.

Rotational Symmetry

An object that looks the same after a certain amount of rotation.

Reflectional Symmetry

An object where one half is the reflection of the other half.

Congruent Figures

Figures that have the same size and same shape. Their corresponding angles and sides are equal.

Rate Of Change

Often considered the slope, this is the comparison of two different quantities that are changing.

Face

One of the polygons that makes up a geometric solid.

Rate

The amount of increase or decrease in a function usually written as a fraction.

Whole

The counting numbers, together with 0, are called the _____ numbers.

Distance Formula

The formula used to find the length between two points in a coordinate plane.

Midpoint Formula

The formula used to find the point that lies half-way between two points in a coordinate plane.

Slope Formula

The formula used to find the rate of change between two points.

Preimage

The original object or figure before a transformation has taken place.

Intercepts

The points on the x and y-axis where the graph crosses the axis.

Image

The resulting object or figure after a transformation has taken place.

Edge

The segment formed by the intersection of two faces in a geometric solid.

Circle

The set of points in a plane that are equidistant from a given point.

Legs

The sides of a right triangle that form the right angle.

Coordinate Geometry

The study of geometry using ordered pairs is called _______ geometry.

Congruent

These are angles, segments, triangles etc. that have exactly the same measures.

Angle

These are two rays sharing a common endpoint. They are typically measured in degrees or radians.

Geometric Transformation

This can be a reflection, rotation, translation, or dilation.

Slope

This describes how much a line rises or falls between any two points on that line. Algebraically it is expressed as (y2 - y1)/ (x2 - x1) for the line passing through (x1, y1) and (x2, y2).

Euler's Formula

This formula shows us that faces + vertices = edges + 2 for solid figures.

Polygon

This is a closed plane figure formed by three or more line segments that do not cross over each other.

Equation Of A Circle

This is a conic section. The standard form is (x - h)squared + (y - k)squared = (r)squared.

Symmetrical Figures

This is a figure that can be folded flat along a line so that the two halves match perfectly.

Concave Polygon

This is a figure with at least three sides which only intersect at their endpoints and no adjacent sides are collinear; and a diagonal that connects two nonconsecutive endpoints can contain points outside the polygon.

Convex Polygon

This is a figure with at least three sides which only intersect at their endpoints and no adjacent sides are collinear; and a diagonal that connects two nonconsecutive endpoints cannot contain points outside the polygon, the entire diagonal is contained within the polygon.

Plane

This is a flat surface extending in all directions.

Radius

This is a line segment between the center and a point on the circle or sphere.

Coordinate Plane

This is a plane with two axes as a frame of reference. The x-axis is a horizontal line and the y-axis is perpendicular to it (i.e., the y-axis is vertical). The intersection of the two axes is called the origin.

Triangle

This is a polygon with three sides.

Parallelogram

This is a quadrilateral that contains two pairs of parallel sides.

Rectangle

This is a quadrilateral with four congruent angles (all 90°).

Acute Triangle

This is a triangle in which all of the angles are less than 90°.

Right Triangle

This is a triangle which has one 90-degree angle.

Equilateral

This is a triangle with all sides equal in length.

Isosceles

This is a triangle with exactly two congruent sides.

Scalene

This is a triangle with three unequal sides.

Ordered

This is a way of expressing a relationship between x and y in set notation. It is called an ____ pair.

Obtuse

This is an angle having a measure greater than 90° and up to 180°.

Acute Angle

This is an angle whose measure is between 0 degrees and 90 degrees.

Right

This is an angle whose measure is exactly 90°.

Estimation

This is an approximate calculation of quantity or degree or worth.

Slope-Intercept Form

This is an equation of a line in the form y=mx+b.

Reflection

This is flipping a figure over the axis of symmetry. Every point has a corresponding point in the new image on the opposite side of the axis of symmetry, except when the point lies on the axis.

Area Of A Circle

This is found by multiplying pi by the radius squared.

Rotation

This is moving a figure around a fixed point, which may be inside, on the edge, or outside the figure. Movement may be clockwise or counterclockwise.

Quadrant

This is one of four sections formed by the intersection of the x-axis and y-axis on a Cartesian coordinate plane.

Translation (a)

This is sliding a given figure in a certain direction, movement of the figure is shown by vectors. This is an isometry.

Area

This is the extent of a 2-dimensional shape enclosed within a boundary. Measured in length units squared (cm2; or in2; etc).

X-Axis

This is the horizontal axis in a coordinate graph.

Coordinates

This is the pair of numbers giving the location of a point.

Origin

This is the point where the x-axis crosses the y-axis. The coordinate location is the ordered pair (0,0).

Space

This is the set of all points. It is made up of an infinite number of planes.

Perimeter

This is the sum of the lengths of all the sides of a polygon, expressed in linear units.

Y-Axis

This is the vertical axis in a coordinate graph.

System Of Equations

This is two or more equations with common variables, also known as a linear system.

Turn

This is what we call rotating a shape around a point. Another name for this is a rotation.