How can we help?

You can also find more resources in our Help Center.

adjacent angle

angle bisector

collinear

complementary angles

Two angles in a plane which share a common vertex and a commo…

A line or ray that divides an angle in half. For polygons, a…

Lying on the same line.

Two acute angles that add up to 90°.

adjacent angle

Two angles in a plane which share a common vertex and a commo…

angle bisector

A line or ray that divides an angle in half. For polygons, a…

opposite reciprocal

circumcenter of a triangle

circumscribed circle

incenter of a triangle

The slope of one perpendicular line is the _____ of the other…

The point of concurrency of the three perpendicular bisectors…

A circle that contains all the vertices of a polygon

The point of concurrency of the three angle bisectors of a tr…

opposite reciprocal

The slope of one perpendicular line is the _____ of the other…

circumcenter of a triangle

The point of concurrency of the three perpendicular bisectors…

Biconditional

Compound statement

conclusion

conjecture

the combination of a conditional statement and its converse.…

combines two or more statements

the part of an if-then statement (conditional) that follows t…

a conclusion reached by using inductive reasoning

Biconditional

the combination of a conditional statement and its converse.…

Compound statement

combines two or more statements

Triangle Sum Conjecture

Auxiliary line

Legs

Isosceles Triangle Conjecture

The sum of the measures of the angles in every triangle is 180°

An extra line or segment that helps with a proof

The other two sides of an isosceles triangle that are not the…

If a triangle is isosceles, then its base angles are congruent

Triangle Sum Conjecture

The sum of the measures of the angles in every triangle is 180°

Auxiliary line

An extra line or segment that helps with a proof

Point

line

Ray

Obtuse Angle

an exact location that has no size

A straight, unbroken set of points that goes on forever. It h…

A part of a line, with one endpoint, that continues without e…

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

Point

an exact location that has no size

line

A straight, unbroken set of points that goes on forever. It h…

Equilateral Triangle

Isosceles Triangle

Scalene Triangle

Equiangular Triangle

A triangle with three congruent sides.

A triangle with at least two congruent sides.

A triangle with no sides congruent.

A triangle with three congruent angles.

Equilateral Triangle

A triangle with three congruent sides.

Isosceles Triangle

A triangle with at least two congruent sides.

base of a parallelogram

height of a parallelogram

base of a triangle

height of a triangle

any side of a parallelogram

perpendicular distance between bases

any side of a triangle

the length of an altitude drawn to a given base

base of a parallelogram

any side of a parallelogram

height of a parallelogram

perpendicular distance between bases

ratio

proportion

similar

scale factor

The ____ of one number to another is the quotient when the fi…

A _____ is an equation stating that two ratios are equal. (ex…

Two polygons are ____ if their vertices can be paired so that…

If two polygons are similar, then the ratio of the lengths of…

ratio

The ____ of one number to another is the quotient when the fi…

proportion

A _____ is an equation stating that two ratios are equal. (ex…

circle

chord

diameter

radius

the set of all points in a plane that are equidistant from a…

a segment whose endpoints are on the circle.

a chord that passes through a center and the other endpoints…

a segment where one endpoint is at the center and the other e…

circle

the set of all points in a plane that are equidistant from a…

chord

a segment whose endpoints are on the circle.

line segment

ray

plane

line

Part of a line consisting of two points and all the points be…

The part of a line that starts at an end point and extends fo…

Flat surface that has no thickness and extends forever. Name:…

Straight path that has no thickness and extends forever. Name…

line segment

Part of a line consisting of two points and all the points be…

ray

The part of a line that starts at an end point and extends fo…

Midsegment Theorem

Perpendicular Bisector Theorem

Converse of the Perpendicular Bisector…

Circumcenter Theorem

The segment connecting the midpoints of two sides of a triang…

In a plane, if a point is on the perpendicular bisector of a…

In a plane, if a point is equidistant from the endpoints of a…

The perpendicular bisectors of a triangle intersect at a poin…

Midsegment Theorem

The segment connecting the midpoints of two sides of a triang…

Perpendicular Bisector Theorem

In a plane, if a point is on the perpendicular bisector of a…

actue triangle

Acute Angle

angle

angle bisector

a triangle with all angles less than 90 degrees

Angle measuring less than 90 degrees

formed by two rays that share an endpoint so long as they do…

a ray that shares the vertex of the angle and divides the ang…

actue triangle

a triangle with all angles less than 90 degrees

Acute Angle

Angle measuring less than 90 degrees

Transversal

Corresponding Angles

Alternate Interior Angles

Alternate Exterior Angles

A line that intersects two or more coplanar lines at differen…

Two non-adjacent angles that lie on the same side of the tran…

Two non-adjacent angles that lie on the opposite sides of the…

Two non-adjacent angles that lie on the opposite sides of the…

Transversal

A line that intersects two or more coplanar lines at differen…

Corresponding Angles

Two non-adjacent angles that lie on the same side of the tran…

Point

Line

Plane

Definition

It is a location in space. (like the tip of a pencil or GPS l…

A straight, continuous arrangement of infinitely many points.…

Has length and width but no thickness. Contains at least thre…

A statement that clarifies or explains the meaning of a word…

Point

It is a location in space. (like the tip of a pencil or GPS l…

Line

A straight, continuous arrangement of infinitely many points.…

acute triangle

equiangular triangle

obtuse triangle

right triangle

A triangle with 3 acute angles

a triangle with three congruent angles

a triangle with one obtuse angle

a triangle with one right angle

acute triangle

A triangle with 3 acute angles

equiangular triangle

a triangle with three congruent angles

Disc

Right triangular Prism

Oblique Triangular Prism

Right Rectangular Prism

A _____ is the set of all points on a circle and in the inter…

A triangle translated through space in a direction perpendicu…

A slanted triangular prism.

A rectangle translated through space in a direction perpendic…

Disc

A _____ is the set of all points on a circle and in the inter…

Right triangular Prism

A triangle translated through space in a direction perpendicu…

point

line

collinear points

plane

an exact location with no size, only position. It is represen…

a straight continuous arrangement of an infinite number of po…

points located on the same line

a flat surface having infinite length but no width.

point

an exact location with no size, only position. It is represen…

line

a straight continuous arrangement of an infinite number of po…

adjacent angle

acute angle

angle bisector

angle

Two angles that share a common vertex and side, but have no c…

An angle that has a measure greater than 0⁰ and less than 90⁰

A ray that divides an angle into two angles that are congruent

A set of points consisting of two different rays that... have th…

adjacent angle

Two angles that share a common vertex and side, but have no c…

acute angle

An angle that has a measure greater than 0⁰ and less than 90⁰

Ruler Postulate

Segment Addition Postulate

Reflexive Property of Congruence

Symmetric Property of Congruence

The points on a line can be put into a one-to-one corresponde…

If three points A, B, and C are collinear and B is between A…

For any segment AB, AB = AB... For any angle A, m∠A = m∠A

If AB = CD, then CD = AB... if ∠A ≅ ∠B, then ∠B ≅ ∠A

Ruler Postulate

The points on a line can be put into a one-to-one corresponde…

Segment Addition Postulate

If three points A, B, and C are collinear and B is between A…

What is a tangent to a circle?

What is the point of tangency?

If a line is tangent to a circle...

If a line in the plane of a circle is…

A line in the plane of the circle that intersects the circle…

The point where the circle and tangent intersect.

then the line is perpendicular to the radius drawn to the poi…

then the line is tangent to the circle.

What is a tangent to a circle?

A line in the plane of the circle that intersects the circle…

What is the point of tangency?

The point where the circle and tangent intersect.

point

line

plane

collinear points

no dimension, named with one letter, designated by a dot

one dimension, named with two letters with an arrow over the…

two dimensions, named with three letters, designated by a sha…

points on the same line

point

no dimension, named with one letter, designated by a dot

line

one dimension, named with two letters with an arrow over the…

circle

center

radius

diameter

A round plane figure whose boundary consists of points equidi…

The point inside a circle that is the same distance from ever…

A line segment with one endpoint at the center of a circle an…

A chord that passes through the center of the circle.

circle

A round plane figure whose boundary consists of points equidi…

center

The point inside a circle that is the same distance from ever…

equidistant

concurrent

circumscribe

inscribe

The same distance from (each other or in relation to other th…

Meeting or tending to meet at the same point.

To draw on the outside of, touching as many points as possible.

To draw on the inside of, touching as many points as possible.

equidistant

The same distance from (each other or in relation to other th…

concurrent

Meeting or tending to meet at the same point.

conjecture

counterexample

inductive reasoning

truth value

an educated guess based on known information

an example that shows a conjecture is false. ... EXAMPLE: Someon…

looking at several specific situations to arrive at a conject…

the truth or falsity of a statement (T or F)

conjecture

an educated guess based on known information

counterexample

an example that shows a conjecture is false. ... EXAMPLE: Someon…

counterexample

right angle

acute angle

obtuse angle

an example that shows that a conjecture is incorrect or that…

an angle that measures 90 degrees

an angle that measures less than 90 degrees

an angle that measures more than 90 degrees but less than 180…

counterexample

an example that shows that a conjecture is incorrect or that…

right angle

an angle that measures 90 degrees

Isosceles Triangle Legs

Isosceles Triangle Base

Isosceles Triangle Vertex Angle

Isosceles Triangle Base Angle

The two sides of an isosceles triangle that are congruent.

The side of an isosceles triangle that is opposite the vertex…

An angle having the legs of an isosceles triangle as sides.

An angle formed by the base and leg of an isosceles triangle.

Isosceles Triangle Legs

The two sides of an isosceles triangle that are congruent.

Isosceles Triangle Base

The side of an isosceles triangle that is opposite the vertex…

Radius

Diameter

Chord

Secant

The distance from the center of a circle to any point on the…

A chord that passes through the center of the circle

a segment whose endpoints are on a circle

A line that intersects a circle in two points

Radius

The distance from the center of a circle to any point on the…

Diameter

A chord that passes through the center of the circle

angle

parallel lines

perpendicular lines

line segment

Formed by two rays sharing a common endpoint

Two distinct coplanar lines that do not intersect

Two coplanar lines whose point of intersection creates the ve…

The set of points marking the shortest distance between two p…

angle

Formed by two rays sharing a common endpoint

parallel lines

Two distinct coplanar lines that do not intersect

Angle addition postulate

Segment addition postulate

Linear Pair Postulate

Vertical Angles Theorem

Measure of an angle equals sum of pairs

Measure of a segment equals sum of its parts

If two angles form a linear pair then they are supplementary

Vertical angles are congruent

Angle addition postulate

Measure of an angle equals sum of pairs

Segment addition postulate

Measure of a segment equals sum of its parts

acute triangle

equiangular triangle

obtuse triangle

right triangle

A triangle with 3 acute angles

a triangle with three congruent angles

a triangle with one obtuse angle

a triangle with one right angle

acute triangle

A triangle with 3 acute angles

equiangular triangle

a triangle with three congruent angles

angle bisector

perpendicular bisector

perpendicular

midpoint

a ray, line, or segment that divides an angle into two congru…

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

At an angle of 90˚ to a given line, plane, or surface.

A point that divides a segment into two congruent segments

angle bisector

a ray, line, or segment that divides an angle into two congru…

perpendicular bisector

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

angle

parallel

coplanar

parallel lines

A figure formed by two rays with a common endpoint

an object exactly in line with another, and will never cross…

points that lie on the same plane

lines that do not intersect and are coplanar

angle

A figure formed by two rays with a common endpoint

parallel

an object exactly in line with another, and will never cross…

angle bisector

conditional statement

converse

inverse

a line from the vertex of an angle that bisects the angle

this is a statement that has two parts (the hypothesis and co…

this is formed by switching the hypothesis and the conclusion…

-p to -q

angle bisector

a line from the vertex of an angle that bisects the angle

conditional statement

this is a statement that has two parts (the hypothesis and co…

transformation

reflection

line of reflection

isometry

In a pane, a mapping for which each point has exactly one ima…

A transformation representing a flip of the figure over a poi…

A line through a figure that separates the figure into two mi…

A mapping for which the original figure and its image are con…

transformation

In a pane, a mapping for which each point has exactly one ima…

reflection

A transformation representing a flip of the figure over a poi…

Tangent line to a circle Theorem

External Tangent Conruence Theorem

Arc addition postulate

Congruent Circles Theorem

In a plane, a line is tangent to a circle if and ony if the l…

Tangent segments from a common external point are conruent

The measure of an arc formed by two adjacent arcs is the sum…

Two circles are congruent circles if and only if they have th…

Tangent line to a circle Theorem

In a plane, a line is tangent to a circle if and ony if the l…

External Tangent Conruence Theorem

Tangent segments from a common external point are conruent

Angle Bisector

Incenter

Point of Concurrency

Concurrent Lines

a ray that divides an angle into two congruent angles

in a triangle; intersection of angle bisectors, center of ins…

the point of intersection of concurrent lines

Three or more lines that intersect at a common point

Angle Bisector

a ray that divides an angle into two congruent angles

Incenter

in a triangle; intersection of angle bisectors, center of ins…