Basic Geometry Terms

Question 1

Collinear Points

Answer 1

Three or more points that belong to the same line

Question 2

Line segment

Answer 2

A set of two points and all of the points between them

Question 3

Ray

Answer 3

A set of points consisting of a fixed point of a line and all the points of the line on the same side of the fixed point

Question 4

Opposite rays

Answer 4

Two rays of the same line that have common endpoint and no other point in common

Question 5

Angle

Answer 5

A set of points consisting of the union of two disctint non-collinear rays with a common endpoint.

Question 6

Congruent line segment

Answer 6

Line segments that are equal in measure

Question 7

Congruent angles

Answer 7

Angles that are equal in measure

Question 8

Midpoint

Answer 8

The point of a line segment that forms two congruent segments

Question 9

Line segment bisector

Answer 9

Line, line segment, or ray that intersects that line segment at its midpoint.

Question 10

Right angle

Answer 10

An angle measuring 90 degrees.

Question 11

Acute angle

Answer 11

An angle whose measure is less than 90 degrees but greater than 0 degrees

Question 12

Obtuse angle

Answer 12

An angle whose measure is more than 90 degrees but less than 180 degrees.

Question 13

Complementary angles

Answer 13

Two angles, the sum whose measure is 90 degrees

Question 14

Supplementary angles

Answer 14

Two angles, the sum of whose measure is 180 degrees

Question 15

Intersecting lines

Answer 15

Two lines that have a point in common

Question 16

Concurrent lines

Answer 16

Three or more lines that contain the same point

Question 17

Parallel lines

Answer 17

Two lines that lie in the same plane and do not intersect

Question 18

Perpendicular lines

Answer 18

Two lines that intersect and form a right angle

Question 19

Angle bisector

Answer 19

A ray (or part of a line) whose endpoint is the vertex of the angle and that forms two congruent angles.

Question 20

Adjacent angles

Answer 20

Two angles in the same plane that share a common vertex and a common ray, but no other points.

Question 21

Vertical angles

Answer 21

A pair of angles that share a single vertex but open in opposite directions

Question 22

Linear Pair

Answer 22

Two adjacent angles such that their non-common rays are mutually opposite form a linear pair