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Welcome to Areas, Plane Geometry Index. Site created and maintained by Antonio Gutierrez.

 

Areas - Table of Content

 

The School of Athens

81.

Quadrilateral with Midpoints, Triangles Area

Proposed Problem 174. Quadrilateral with Midpoints, Triangles, Areas.  

80.

Quadrilateral with Midpoints, Triangles Area

Proposed Problem 173. Quadrilateral with Midpoints, Triangles, Areas.  

79.

Elearning 172: Trapezoid, Quadrilateral, Area

Proposed Problem 172. Trapezoid, Midpoints, Quadrilaterals, Areas.  

78.

Elearning 172: Trapezoid, Midpoints, Quadrilaterals, Areas

Proposed Problem 171. Trapezoid, Midpoints, Triangles, Areas.  

77.

Trapezoid, Triangle, Area

Proposed Problem 170. Trapezoid, Midpoint, Triangle, Area.  

76.

Geometry Problem: Parallelogram, Triangles, Pentagon, Area

Proposed Problem 169. Parallelogram, Interior and Exterior Points, Diagonals, Pentagon, Triangles, Areas  

75.

Geometry Problem: Parallelogram, Triangles, Pentagon, Area

Proposed Problem 168. Parallelogram, Diagonal, Triangles, Pentagon, Areas.  

74.

Geometry Problem: Parallelogram, Triangles, Area

Proposed Problem 167. Parallelogram, Diagonal, Triangles, Areas.  

73.

Geometry Problem: Parallelogram, Triangles, Area

Proposed Problem 166. Parallelogram, Diagonal, Triangles, Areas.  

72.

Elearning 165: Parallelogram area

Proposed Problem 165. Parallelogram, Diagonal, Triangles, Areas.  

71.

Elearning 164: Parallelogram, Triangles, Area

Proposed Problem 164. Parallelogram, Trapezoid, Diagonal, Triangles, Areas.  

70.

Elearning 163 Trapezoid, Triangles, Area

Proposed Problem 163. Trapezoid, Diagonals, Triangles, Areas.  

69.

Elearning 162 Parallelogram and Triangles Areas

Proposed Problem 162. Parallelogram, Triangles, Areas.  

68.

Elearning 161 Parallelogram and Octagon Areas

Proposed Problem 161. Parallelogram, Midpoints, Octagon, Areas.  

67.

Quadrilateral area, trisection

Proposed Problem 151. Quadrilateral, Area, Trisection of Sides.  

66.

Quadrilateral area, trisection

Proposed Problem 150. Quadrilateral, Area, Trisection of Sides.  

65.

Quadrilateral Area, Midpoint, Elearning

Proposed Problem 149. Quadrilateral, Area, Midpoints.  

64.

Quadrilateral area, Midpoint, Elearning

Proposed Problem 148. Quadrilateral, Area, Midpoints.  

63.

Quadrilateral Area, Elearning

Proposed Problem 147. Quadrilateral, Area, Midpoints, Triangle.  

62.

Quadrilateral Area, Midpoint

Proposed Problem 146. Varignon's Theorem: Quadrilateral, Midpoints, Parallelogram, Area, Perimeter.  

61.

Elearning 142: Triangle area

Proposed Problem 142. Four Triangles, Incircle, Tangent and Parallel to Side, Areas.  

60.

Elearning 139: Triangle Area

Proposed Problem 139. Triangle Area, Orthic Triangle, Semiperimeter, Circumradius.  

59.

Right Triangles, Formulas and Facts
Pythagorean theorem, Similarity, Geometric mean, hypotenuse, legs, semiperimeter, altitude, median, similar shapes areas, centers, orthocenter, incenter, centroid, circumcenter, radius, inradius, circumradius, exradius, circles, incircle, circumcircle, excircle.

58.

Pythagoras Theorem, 47th Proposition of Euclid's Book I

Pythagorean Theorem, 47th Proposition of Euclid's Book I, Video.

57.

Heron's Formula.
Key facts and
a purely geometric step-by-step proof.
 

56.

Heron's Formula with medians 

55.

Kurschak's Tile and Theorem. Jozsef Kurschak (Hungary, 1864-1933) An elegant and a purely geometric way of finding the area of a regular dodecagon.
 

54.

Archimedes' Book of Lemmas. Exercise your brain. Archimedes wrote the "Book of Lemmas" more than 2200 years ago. Solve these 15 high school level problems and lift up your geometry skills.
 
Proposition 4 Arbelos

53.

Archimedes Proposition 7. Circles and Squares

52.

Proposition 14 area of the Salinon.

51.

Brahmagupta's Formula  Area of a cyclic quadrilateral.

50.

Brahmagupta Formula Extension Area of any quadrilateral.

49.

Pythagoras curiosity. Online tutoring.

The Pythagorean Curiosity Triangles and squares, fifteen conclusions.

48.

Hippocrates and Squaring the Circle
 

47.

Lunes of Hippocrates 4
 

46.

Lunes of Hippocrates 3
 

45.

Lunes of Hippocrates 2
 

44.

Lunes of Hippocrates 1
 

43.

Pythagoras and Circle Area
 

42.

De Gua's Theorem

41.

Triangle and Squares 22
 

40.

Triangle and Squares 21
See also: Triangle and Squares 19

39.

Triangle and Squares 20

38.

Triangle and Squares 19  

37.

Triangle and Squares 18  Sangaku Problem

36.

Cyclic Quadrilateral: Ratio of the Diagonals
 

35.

Ptolemy's Theorem.
 

34.

Marion Walter's Theorem: Triangle and Hexagon areas: Using TracenPoche Dynamic Geometry Software

33.

Elearning 125: Area

Proposed Problem 125. Area of Triangle, Star, Trisection of Sides.

32.

Elearning 124: Triangle Area, Similarity

Proposed Problem 124. Area of triangle, Similarity, Trisection of Sides.

31.

Elearning 123: Triangle Similarity, Area

Proposed Problem 123. Area of triangle, Similarity, Trisection of Sides.

30.

Marion Walter's Theorem

Proposed Problem 122. Marion Walter's Theorem. Area of triangle and Hexagon, Trisection of Sides.

29.

Elearning 121: Similarity and Area

Proposed Problem 121. Similarity and Area of triangle, Trisection of Sides.

28.

Problem 120: Triangle area. Elearning.

Proposed Problem 120. Area of triangle, incenter, excircles, tangent.

27.

Elearn 119: Triangle area.

Proposed Problem 119. Area of triangle, incenter, excircle, tangent.

26.

Problem 118

Proposed Problem 118. Area of triangle, incenter, excenter, tangent.

25.

Elearning 117 Areas

Proposed Problem 117. Area of triangle, incenter, excircles, tangent.

24.

Geometry Problem 116

Proposed Problem 116. Area of triangle, excircles, tangent.

23.

Elearning 115: Problem

Proposed Problem 115. Area of triangle, excircles, tangent.

22.

Elearning 114: Area

Proposed Problem 114. Area of triangle, incircle, excircle.

21.

Elearning 113: Areas

Proposed Problem 113. Area of triangle, incircle, excircle.

20.

Area of Square and triangle, Elearning.

Proposed Problem 112. Area of square and triangle.

519.

Contact Triangle Area. Elearning.

Proposed Problem 110. Area of Contact Triangle.

18.

Elearning 103.

Proposed Problem 103.Equilateral Triangle Area, Interior Point, Heron's Formula.

17.

Problem 102. Elearning, Online Tutoring

Proposed Problem 102.Equilateral Triangle Area, Interior Point.

16.

Circle area problem. Elearning 100

Proposed Problem 100. Circle Area, Archimedes' Book of Lemmas.

15.

Circle area and Pythagoras

Proposed Problem 99: Circle Area, General Extension to Pythagoras' Theorem.

14.

Quadrilateral Area, Elearning.

Proposed Problem 98. Quadrilateral Area, Centroid, Similarity.

13.

Elearning 97

Proposed Problem 97. Similar Triangles, Areas.

12.

Geometry problem

Proposed Problem 90. Quadrilateral and Triangle Areas, Midpoints.

11.

Math problem

Proposed Problem 89. Triangles of equal area, Midpoints.

10.

Math problem

Proposed Problem 88. Triangle and Quadrilateral Areas, Midpoints.

9.

Quadrilateral area problem

Proposed Problem 87. Area of Quadrilaterals and Midpoints of Diagonals.

8.

Proposed Problem 86. Intouch and Extouch Triangles, Areas.

7.

Proposed Problem 85. Contact Triangles Areas, Incircle, Excircle.

6.

Proposed Problem 84. Contact Triangles Areas, Incircle, Excircle, Inradius, Exradius.

5.

Proposed Problem 83. Area of the Excircle Contact Triangle, exradius, circumradius.

4.

Contact triangle area

Proposed Problem 82. Area of the Contact Triangle, inradius, circumradius.

3.

Triangle area

Proposed Problem 81. Area of a triangle, side, inradius, circumradius.

2.

Proposed Problem 80. Area of a triangle, side, incircle, inradius.

1.

Proposed Problem 76: Area of a Circle. Square, Circle, Circular Sector.

 

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Last updated: September 7, 2008