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Flat (geometry)

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544: 388: 601:. Two parallel flats of the same dimension either coincide or do not intersect; they can be described by two systems of linear equations which differ only in their right-hand sides. 239: 399: 695:
or dual Grassmann coordinates. For example, a line in three-dimensional space is determined by two distinct points or by two distinct planes.
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If flats do not intersect, and no line from the first flat is parallel to a line from the second flat, then these are
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defines a plane, while a pair of linear equations can be used to describe a line. In general, a linear equation in
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The aforementioned facts do not depend on the structure being that of Euclidean space (namely, involving
1045: 153: 30:"Euclidean subspace" redirects here. For a subspace that contains the zero vector or a fixed origin, see 822: 192:. For example, a line in two-dimensional space can be described by a single linear equation involving 189: 261: 1050: 1055: 122: 597:
If each line from one flat is parallel to some line from another flat, then these two flats are
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are points, lines, planes, and the space itself. The definition of flat excludes non-straight
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There is the distance between two flats, equal to 0 if they intersect. (See for example
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variables describes a hyperplane, and a system of linear equations describes the
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that is itself an affine space. Particularly, in the case the parent space is
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and can build systematic coordinates for flats in any dimension, leading to
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on the left-hand side and a third parallel line on the right-hand side.
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there exists the minimal flat which contains them, of dimension at most
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There is the distance between a flat and a point. (See for example
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of those hyperplanes. Assuming the equations are consistent and
383:{\displaystyle x=2+3t,\;\;\;\;y=-1+t\;\;\;\;z={\frac {3}{2}}-4t} 393:
while the description of a plane would require two parameters:
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In three-dimensional space, a single linear equation involving
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In general, a parameterization of a flat of dimension
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to distinguish it from other manifolds or varieties.
576: 997: 290:A flat can also be described by a system of linear 92:; flats one dimension lower than the parent space, 538: 382: 233: 904:Gallier, J. (2011). "Basics of Affine Geometry". 839:between two flats, which belongs to the interval 535: 1037: 152:, as geometric realizations of solution sets of 1016: 731:is a point not lying on the same plane, then 683:) make the set of all flats in the Euclidean 698:However, the lattice of all flats is not a 670: 495: 494: 493: 492: 450: 449: 448: 447: 354: 353: 352: 351: 332: 331: 330: 329: 667:minus the dimension of the intersection. 534: 272:equations describes a flat of dimension 903: 14: 1038: 947: 582:Intersecting, parallel, and skew flats 137:having different notions of distance: 1017: 998: 974:Primitives for Computational Geometry 788: 763:, both representing a line. But when 675:These two operations (referred to as 121:, and the plane itself; the flats in 918:An affine subspace is also called a 27:Affine subspace of a Euclidean space 24: 906:Geometric Methods and Applications 25: 1067: 991: 590:of flats is either a flat or the 577:Operations and relations on flats 808:Distance from a point to a plane 853:(between two planes). See also 814:Distance from a point to a line 183: 178: 897: 13: 1: 931: 285: 188:A flat can be described by a 61:which inherits the notion of 950:Oriented Projective Geometry 944:, Krieger, New York, page 7. 616:For two flats of dimensions 167:, and is sometimes called a 113:(two-dimensional space) are 7: 914:10.1007/978-1-4419-9961-0_2 863: 154:systems of linear equations 10: 1072: 978:DEC SRC Research Report 36 829:Skew lines Β§ Distance 823:Distance between two lines 190:system of linear equations 29: 797:) and are correct in any 890: 826:(in the same plane) and 801:. In a Euclidean space: 671:Properties of operations 234:{\displaystyle 3x+5y=8.} 65:from its parent space. 611: 123:three-dimensional space 948:Stolfi, Jorge (1991), 908:. New York: Springer. 540: 384: 235: 49:, i.e. a subset of an 938:Heinrich Guggenheimer 841:[0, π/2] 693:Grassmann coordinates 541: 385: 236: 972:Ph.D. dissertation, 856:Angles between flats 700:distributive lattice 400: 305: 292:parametric equations 266:linearly independent 207: 942:Applicable Geometry 870:N-dimensional space 847:. (See for example 777:are parallel, this 100:-flats, are called 1046:Euclidean geometry 1019:Weisstein, Eric W. 1000:Weisstein, Eric W. 983:2021-10-17 at the 843:between 0 and the 795:Euclidean distance 789:Euclidean geometry 536: 380: 231: 73:-dimensional space 59:Euclidean subspace 18:Euclidean subspace 963:978-0-12-672025-9 557:parameters, e.g. 369: 165:algebraic variety 98: βˆ’ 1) 16:(Redirected from 1063: 1032: 1031: 1013: 1012: 966: 925: 924: 922:by some authors. 901: 842: 784: 776: 769: 762: 730: 726: 716:intersect, then 715: 708: 686: 666: 650: 633: 624: 572: 556: 552: 545: 543: 542: 537: 530: 529: 514: 513: 491: 490: 475: 474: 443: 442: 427: 426: 389: 387: 386: 381: 370: 362: 281: 271: 259: 255: 251: 247: 240: 238: 237: 232: 199: 195: 145:, respectively. 99: 91: 85: 79:-flats of every 78: 72: 21: 1071: 1070: 1066: 1065: 1064: 1062: 1061: 1060: 1051:Affine geometry 1036: 1035: 994: 985:Wayback Machine 976:, available as 967: 964: 934: 929: 928: 902: 898: 893: 866: 840: 791: 782: 775: 771: 768: 764: 756: 748: 740: 736: 732: 728: 727:is a point. If 725: 721: 717: 714: 710: 707: 703: 702:. If two lines 684: 673: 665: 658: 652: 648: 641: 635: 632: 626: 623: 617: 614: 584: 579: 570: 564: 558: 554: 550: 525: 521: 509: 505: 486: 482: 470: 466: 438: 434: 422: 418: 401: 398: 397: 361: 306: 303: 302: 288: 273: 269: 257: 253: 249: 245: 208: 205: 204: 197: 193: 186: 181: 169:linear manifold 148:Flats occur in 143:geodesic length 129:and non-planar 109:The flats in a 93: 87: 83: 76: 70: 47:affine subspace 35: 32:Linear subspace 28: 23: 22: 15: 12: 11: 5: 1069: 1059: 1058: 1056:Linear algebra 1053: 1048: 1034: 1033: 1014: 993: 992:External links 990: 989: 988: 968:From original 962: 954:Academic Press 945: 933: 930: 927: 926: 916:. p. 21: 895: 894: 892: 889: 888: 887: 882: 877: 872: 865: 862: 861: 860: 850:Dihedral angle 833: 818: 790: 787: 781:fails, giving 779:distributivity 773: 766: 754: 746: 738: 734: 723: 719: 712: 705: 672: 669: 663: 656: 646: 639: 630: 621: 613: 610: 583: 580: 578: 575: 568: 562: 553:would require 547: 546: 533: 528: 524: 520: 517: 512: 508: 504: 501: 498: 489: 485: 481: 478: 473: 469: 465: 462: 459: 456: 453: 446: 441: 437: 433: 430: 425: 421: 417: 414: 411: 408: 405: 391: 390: 379: 376: 373: 368: 365: 360: 357: 350: 347: 344: 341: 338: 335: 328: 325: 322: 319: 316: 313: 310: 287: 284: 268:, a system of 242: 241: 230: 227: 224: 221: 218: 215: 212: 185: 182: 180: 177: 173:linear variety 150:linear algebra 57:, a flat is a 26: 9: 6: 4: 3: 2: 1068: 1057: 1054: 1052: 1049: 1047: 1044: 1043: 1041: 1029: 1028: 1023: 1020: 1015: 1010: 1009: 1004: 1001: 996: 995: 986: 982: 979: 975: 971: 965: 959: 955: 951: 946: 943: 939: 936: 935: 923: 921: 915: 911: 907: 900: 896: 886: 883: 881: 878: 876: 873: 871: 868: 867: 858: 857: 852: 851: 846: 838: 835:There is the 834: 831: 830: 825: 824: 819: 816: 815: 810: 809: 804: 803: 802: 800: 796: 786: 780: 760: 752: 744: 701: 696: 694: 690: 682: 678: 668: 662: 655: 645: 638: 629: 620: 609: 607: 602: 600: 595: 593: 589: 574: 571: 561: 531: 526: 522: 518: 515: 510: 506: 502: 499: 496: 487: 483: 479: 476: 471: 467: 463: 460: 457: 454: 451: 444: 439: 435: 431: 428: 423: 419: 415: 412: 409: 406: 403: 396: 395: 394: 377: 374: 371: 366: 363: 358: 355: 348: 345: 342: 339: 336: 333: 326: 323: 320: 317: 314: 311: 308: 301: 300: 299: 297: 293: 283: 280: 276: 267: 263: 228: 225: 222: 219: 216: 213: 210: 203: 202: 201: 191: 176: 174: 170: 166: 162: 157: 155: 151: 146: 144: 140: 136: 132: 128: 124: 120: 116: 112: 107: 105: 104: 97: 90: 82: 74: 66: 64: 60: 56: 52: 48: 44: 40: 33: 19: 1025: 1006: 1003:"Hyperplane" 973: 949: 941: 919: 917: 905: 899: 854: 848: 827: 821: 812: 806: 799:affine space 792: 758: 750: 742: 697: 680: 676: 674: 660: 653: 643: 636: 627: 618: 615: 603: 596: 588:intersection 585: 566: 559: 548: 392: 289: 278: 274: 262:intersection 243: 187: 184:By equations 179:Descriptions 172: 168: 159:A flat is a 158: 147: 133:, which are 108: 101: 95: 88: 75:, there are 67: 58: 51:affine space 42: 36: 880:Coplanarity 845:right angle 103:hyperplanes 1040:Categories 932:References 606:skew flats 286:Parametric 139:arc length 86:from 0 to 1027:MathWorld 1008:MathWorld 687:-space a 592:empty set 516:− 458:− 429:− 372:− 340:− 296:parameter 135:subspaces 81:dimension 55:Euclidean 981:Archived 970:Stanford 940:(1977), 885:Isometry 864:See also 599:parallel 161:manifold 131:surfaces 63:distance 39:geometry 875:Matroid 689:lattice 163:and an 1022:"Flat" 960:  753:) ∩ (β„“ 252:, and 127:curves 115:points 68:In an 45:is an 891:Notes 837:angle 565:, …, 119:lines 111:plane 958:ISBN 920:flat 811:and 770:and 745:= (β„“ 741:) + 709:and 681:join 679:and 677:meet 625:and 612:Join 196:and 141:and 43:flat 41:, a 910:doi 737:∩ β„“ 722:∩ β„“ 649:+ 1 586:An 171:or 37:In 1042:: 1024:. 1005:. 956:, 952:, 859:.) 832:.) 817:.) 757:+ 749:+ 733:(β„“ 659:+ 642:+ 594:. 573:. 298:: 282:. 277:βˆ’ 248:, 229:8. 200:: 156:. 117:, 106:. 1030:. 1011:. 987:. 912:: 783:p 774:2 772:β„“ 767:1 765:β„“ 761:) 759:p 755:2 751:p 747:1 743:p 739:2 735:1 729:p 724:2 720:1 718:β„“ 713:2 711:β„“ 706:1 704:β„“ 685:n 664:2 661:k 657:1 654:k 647:2 644:k 640:1 637:k 631:2 628:k 622:1 619:k 569:k 567:t 563:1 560:t 555:k 551:k 532:. 527:2 523:t 519:3 511:1 507:t 503:5 500:= 497:z 488:2 484:t 480:2 477:+ 472:1 468:t 464:+ 461:4 455:= 452:y 445:, 440:2 436:t 432:3 424:1 420:t 416:2 413:+ 410:5 407:= 404:x 378:t 375:4 367:2 364:3 359:= 356:z 349:t 346:+ 343:1 337:= 334:y 327:, 324:t 321:3 318:+ 315:2 312:= 309:x 279:k 275:n 270:k 258:n 254:z 250:y 246:x 226:= 223:y 220:5 217:+ 214:x 211:3 198:y 194:x 96:n 94:( 89:n 84:k 77:k 71:n 34:. 20:)

Index

Euclidean subspace
Linear subspace
geometry
affine subspace
affine space
Euclidean
distance
n-dimensional space
dimension
hyperplanes
plane
points
lines
three-dimensional space
curves
surfaces
subspaces
arc length
geodesic length
linear algebra
systems of linear equations
manifold
algebraic variety
system of linear equations
intersection
linearly independent
parametric equations
parameter
intersection
empty set

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