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Hypotenuse

longest side in a right triangle; opposite the right angle

Octagon

8-sided polygon

Scalene Triangle

triangle with no sides equal in length

Hexagon

6-sided polygon

Line Segment

part of a line with two endpoints

Vertex

point where two rays meet

Perpendicular Lines

lines that intersect to form four right angles

Decagon

10-sided polygon

Quadrilateral

4-sided polygon

Equilateral Triangle

triangle with all sides equal in length

Diagonal

connects two non-consecutive vertices

Line

a collection of points extending forever in opposite directions

Triangle

3-sided polygon

Point

an exact location in space

Ray

contains an endpoint and extends forever in the opposite direction

Parallel Lines

two lines that never intersect and are always the same distance apart

Nonagon

9-sided polygon

Pentagon

5-sided polygon

Right Triangle

a triangle that contains a right angle

Isosceles Triangle

a triangle with two sides equal in length

Legs

the two sides of a right triangle that meet to form the right angle

Square

a quadrilateral with 4 equal sides and 4 right angles

Rectangle

a quadrilateral with 4 right angles and opposite sides are parallel and equal in length

Right angle

an angle that is 90 degrees

Trapezoid

a quadrilateral with one pair of parallel sides

Angle

two rays with the same endpoint

Rhombus

a quadrilateral with 4 equal sides and opposite angles equal

Complementary angles

two angles whose sum is 90 degrees

Supplementary angles

two angles whose sum is 180 degrees

Adjacent angles

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

Obtuse angles

angles whose measure is greater than 90 degrees and is less than 180 degrees

Straight angles

an angle whose measure is 180 degrees

Vertical angles

two nonadjacent angles formed by two intersecting lines

Transversal

a line that cuts across a set of lines or the sides of a plane figure

Symmetric

a geometric figure or graph consisting of two parts that are congruent to each other

Skew lines

lines in three dimensional space that do not intersect and are not parallel

Diameter

a line segment between two points on a circle or sphere which passes through the center

Radius

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

Circumference

the distance around the outside of a circle

Plane

a flat surface that can extend forever in length and width, but has no thickness

Coplanar

points or lines that all lie in the same plane

Congruent

planar figures or solid shapes that have the same shape and size

Alternate interior angles

either pair of interior angles lying on opposite sides of the transversal

Alternate exterior angles

either pair of exterior angles lying on opposite sides of the transversal

Corresponding angles

two angles which occupy the same position, such as angles 1 and 5

Acute angle

an angle whose measure is less than 90 degrees

parallelogram

a 4 sided polygon with both pairs of opposite sides equal and opposite angles equal

Flickr Creative Commons Images

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