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ComplementaryAngles

A pair of angles whose measuresadd up to + degrees.

'iameter

(1) The ma-imum distance betweentwo opposite points on a circle. ()

The ma-imum distance between twoantipodal points on a sphere.

!eometricConstruction

A construction of a geometric figureusing only straightedge andcompass. $uch constructions werestudied by the ancient !reeks.

!olden /atio

!enerally represented as 0. !iven arectangle having sides in the ratio10, partitioning the original rectangleinto a s#uare and new rectangle

results in the new rectangle havingsides with the ratio 10. 0 isappro-imately e#ual to 1.12.

!olden /ectangle

A rectangle in which the ratio of thesides is e#ual to the golden ratio.$uch rectangles have many visualproperties and are widely used in artand architecture.

%ypotenuseThe longest side of a right triangle(i.e., the side opposite the rightangle).

3idpointThe point on a line segment thatdivides it into two segments of e#uallength.

4btuse AngleAn angle that measures greater than+ degrees and less than 12degrees.

*arallel

5n two&dimensional 6uclidean space,two lines that do not intersect. 5nthree&dimensional 6uclidean space,parallel lines not only fail to intersect,but also maintain a constantseparation between points closest toeach other on the two lines.

*erimeter

The length around the boundary of aclosed two&dimensional region. Theperimeter of a circle is called itscircumference.

*erpendicularTwo lines, vectors, planes, etc. thatintersect at a right angle.

*i

The ratio of the circumference of a

circle to its diameter. 5t is e#ual to7.1819+....

*lane !eometryThe portion of geometry dealing withfigures in a plane, as opposed tosolid geometry.

*oint

A ero&dimensional mathematicalob"ect that can be specified in n&dimensional spaceusing ncoordinates.

/adius

The distance from the center of acircle to its perimeter, or from thecenter of a sphere to its surface. Theradius is e#ual to half the diameter.

$upplementary Angles:or a given angle, the angle thatwhen added to it totals 12 degrees.

Triangle 5ne#uality The sum of the lengths of any twosides of a triangle must be greater

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than the length of the third side.

Polygons

6#uilateral TriangleA triangle in which all three sides areof e#ual length. 5n such a triangle,the angles are all e#ual as well.

5sosceles TriangleA triangle with (at least) two sides ofe#ual length, and therefore also with(at least) two e#ual angles.

*arallelogramA #uadrilateral with opposite sidesparallel and therefore oppositeangles e#ual.

*olygonA two&dimensional figure thatconsists of a collection of linesegments, "oined at their ends.

;uadrilateral A four&sided polygon.

/ectangleA #uadrilateral with opposite sides ofe#ual lengths, and with four rightangles.

/egular *olygonA polygon in which the sides are allthe same length and the angles all

have the same measure.

/ight Triangle

A triangle that has a right angle. The*ythagorean Theorem is arelationship among the sides of aright triangle.

$#uareA polygon with four sides of e#uallength and at right angles to eachother.

TrapeoidA #uadrilateral with two sidesparallel.

TriangleA three&sided (and three&angled)polygon.

Solid Geometry

ConeA pyramid with a circular crosssection.

Conve- %ull:or a set of points S, the intersectionof all conve- sets containing S.

Cross $ectionThe plane figure obtained by asolid

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regular polygons. There are e-actlyfive *latonic solids.

*olyhedronA three&dimensional solid thatconsists of a collection of polygons,

"oined at their edges.

*rismA polyhedron with two congruentpolygonal faces and with allremaining faces parallelograms.

*yramid

A polyhedron with one face (knownas the base) a polygon and all theother faces< triangles meeting at acommon polygon verte- (known asthe ape-).

$olid !eometryThat portion of geometry dealing withsolids, as opposed to planegeometry.

$phere

The set of all points in three&dimensional space that are locatedat a fi-ed distance from a givenpoint.

$urface A two&dimensional piece of three&dimensional space.

$urface Area

The area of a surface that lies inthree&dimensional space, or the totalarea of all surfaces that bound asolid.

TetrahedronA *latonic solid consisting of foure#uilateral triangles.

=olumeThe amount of space occupied by a

closed three&dimensional ob"ect.

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