Mrs. Daniel s Geometry Vocab List

Mrs. Daniel s Geometry Vocab List

Geometry Definition: a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.

Refectional Symmetry Definition: All of the points on one side of the line exactly match with all of the points on the other side of the line.

Definition: looks that same after you turn the image around a point by less than 180 degrees. The number of times you can turn the image determines the type of rotational symmetry. Rotational Symmetry

Point Definition: Location only; it has no size. How to Name: One capital letter. Example: P

Line Definition: Straight continuous arrangement of infinitely many points. How to Name: Two capital letters with a line with 2 arrows above it. Example:

Plane Definition: Flat surface that extends infinitely along its length and width. How to Name: One capital script (cursive) letter. Example: M

Collinear Definition:On the same line

Coplanar Definition:On the same plane

Ray Definition:A point on a line, and all the points that lie on one side of this point. How to Name: Two capital letters and a line with one arrow above. The endpoint must be the first letter. Example:

Line Segment Definition: Part of line. Does not extend indefinitely. How to Name: Two capital letters and a line on top. Example:

Midpoint Definition:Point on a line segment that is the same distance from both end points. How to Name: One capital letter Example: C

Congruent Definition: Equal. The same length. The same size. The same measure. Drawn with hash marks.

Bisects Definition Divides into two equal, congruent parts. Line: divides into two congruent segments Angle: divides into two congruent angles

Angle Definition: Formed by two rays that share a common endpoint. How to Name: One or three letters. Angle symbol ( ) in front. Example: B or ABC

Vertex Definition: Common endpoint of the two rays in an angle

Perpendicular Definition: Lines that meet at a 90 degree angle. Symbol: For example:

Parallel Definition: Lines that never intersect (cross/touch). Symbol: Example:

Complementary Angles Definition: 2 angles that add up to 90 degrees.

Supplementary Angles Definition: 2 angles that add up to 180 degrees.

Linear Pair of Angles Definition: Two angles on one line. Sum to 180 degrees.

Right Angle Definition: Angle measure of exactly 90 degrees. Symbol: Drawn with a box

Acute Angle Definition: Angle measure of less than 90 degrees.

Obtuse Angle Definition: Angle measure of more than 90 degrees, but less than 180.

Polygon Definition: A closed figure. How to Name: All capital letters. Use as many letter as sides to the polygon. Some Examples:

Diagonal Definition: a line segment drawn from one vertex to another in a polygon.

Concave Definition: Polygon dips inward (Some diagonals can be drawn outside the shape).

Convex Definition: Polygon only points outward. (No diagonals can be drawn outside the shape).

Regular Polygon Definition: A closed figure, with congruent sides and congruent angles. All sides and angles marked congruent.

Perimeter Definition: Sum of the lengths of the sides. Perimeter = 26cm

Right Triangle Definition: A triangle with one 90 degree angle. Marked with box

Acute Triangle Definition: A triangle with three acute angles.

Obtuse Triangle Definition: A triangle with one obtuse angle.

Scalene Triangle Definition: Triangle with no congruent sides. Each side is marked with a different number of hash marks.

Isosceles Triangle Definition: Triangle with at least two congruent sides and two congruent angles. Picture: Marked with two congruent sides and two congruent angles.

Equilateral Triangle Definition: Triangle with three congruent sides and angles. Marked with three congruent sides and three congruent angles.

Quadrilateral Definition: Any closed four sided figure. Some Examples:

Trapezoid Definition: A quadrilateral with exactly one pair of parallel sides. Opposite sides marked parallel.

Kite Definition: A quadrilateral with two distinct pairs of consecutive congruent sides. Sides next to each other marked congruent.

Parallelogram Definition: A quadrilateral with two pairs of parallel sides. Marked parallel and congruent.

Rhombus Definition: Two pairs of parallel sides and 4 congruent sides. Marked parallel and congruent.

Rectangle Definition: Two pairs of parallel sides and 4 congruent angles Marked parallel, congruent and 4 right angles.

Square Definition: 4 congruent sides and 4 congruent angles Marked parallel, congruent and four right angles.

Circle Definition: a set of all points in a plane at a given distance from a given point (center/origin).

Radius Definition: The given distance from center/origin of the circle to the edge.

Diameter Definition: A chord that passes through the origin/center. Picture:

Chord Definition: A line segment whose endpoints lie on the circle. The diameter is the longest chord.

Tangent Definition: A line that touches (intersects) the circle only once. The point the circle touches the circle is named the point of tangency.

Semicircle Definition: Half of a circle.

Space Definition: the set of ALL points; not contained to a flat surface. Space is threedimensional (3 D).

Cylinder

Prism

Sphere

Cone

Pyramid

Hemisphere