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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
2
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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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