Geometry 

Index of Topics

Simple list of web pages I have created for mathematical topics.

1. Sum of 2 sides from a point to ends of line greater than from included point.

2. Triangles with 2 sides & included angle equal (Euclid 1.4)

3. Triangles with 2 angles and included side equal

4. Perpendicular bisector equidistant from ends

5. Triangle greater side subtends greater angle (Euclid 1-18)

6. Triangle sum of angles  = 2 rt. angles (Euclid 1.32)

7. Parallelogram diagonal creates equal triangles  (Euclid  1. 34 - Part) 

8. Shortest distance between point and line

9. Parallelograms on same base between parallels are equal  (Euclid 1.35)

10. Square diagonals create 4 equal triangles

11. Triangles on the same base are equal  (Similar to Euclid Book 1 Prop 35)

12. Triangle area = half base x height

13. Triangle: Isosceles triangle has equal angles

14. Triangles with equal side are identical triangles

15. Construct Perpendicular to a line.

16. Triangle Sum of Sides Compared to Point To Vertices

17. Triangle: Line joining mid-points of triangle is parallel to other side

18. Triangle: Line drawn through 2 sides of triangle parallel to 3rd divide sides proportionally

19. Triangle perpendicular bisectors meet at a single point

20. Triangle altitudes meet at a single point

21. Triangle: Line from right angle to hypotenuse mid-point creates 2 isos. triangle

22. Right Angle Triangle with hypotenuse and one side equal are identical

23. Triangle internal bisector of one angle and the external bisectors of the other two external angles meet at a single point

24. Circle through 3 points

25. Diameter of circle subtends a right angle

26. Triangle: Pythagoras - Right Angle Triangle (Euclid 1.47)

27. Triangle: Nine points of triangle lie upon a circle

28. Triangle angle bisectors meet at a point.

29. Trigonometry - Basics

30. Parallel lines cut by transversal, interior alternate angles are equal

31. Parallel lines cut by transversal, corresponding angles are equal

32. Parallelogram's diagonals bisect each other

33. Transversals with equal intercepts on parallel Lines

34. Triangle medians cut other median 2/3

35. Quantities in proportion are also in proportion by composition

36. Similar triangles 

37. Chord subtends angle twice as big at centre than at circumference of circle

38. Tangent to circle

39. Radian

40. Squares and Circles

41. Solid geometry