This document provides definitions and explanations of key geometry terms related to lines, angles, triangles, quadrilaterals, circles, and other polygons. It defines points, line segments, rays, intersecting lines, perpendicular lines, parallel lines, acute angles, obtuse angles, right angles, complementary angles, supplementary angles, and more. It also explains the properties of different types of triangles, quadrilaterals, circles, and other polygons. Key terms include radius, diameter, chord, arc, sector, circumference, area, perimeter, scalene triangles, isosceles triangles, equilateral triangles, rectangles, squares, rhombuses, trapezoids, parallelograms, hexagons, octagons

1. Philip's Geometry Guide to Success Lines Angles Triangles Quadrilaterals Circles

2. Lines Points Line Segments Rays Lines Intersecting Lines Perpendicular Lines Parallel Lines Skew Lines

3. Points A point is a precise location in space. It is labeled with a letter. Point a Point b Point c Point d

4. Line Segments A line line that starts at one point and ends at another

5. Ray A line that starts at a point and keeps going past the other

6. Intersec t ing Two lines that meet at a point and do not make 90 degree angles

7. Perpendicular The lines intersect at right angles

8. Parallel Lines that never cross and are on the same plane

9. Skew Lines that are not on the same plane

10. Plane A flat surface that goes on forever in all directions and is defined by three points P

11. Angles acute obtuse right straight vertex/vertices complementary supplementary vertical/ opposite adjacent

12. Acute An angle that is less than a 90 degree angle

13. Obtuse An angle that is more than a 90 degree angle

14. Right An angle that is exactly 90 degrees

15. Straight An angle made up by two 90 degree angles

16. Vertex/Vertices The point where the lines to make the angle meet

17. Complementary Two angles that if you add them together you will get 90 degrees 45 45

18. Supplementary Two angles that if added together you get 180 degrees 110 70

19. Vertical/Opposite An angle that is opposite to the same angle

20. Adjacent An angle that is sharing the same vertex with another angle F D E C Angle DFE Angle EFC

21. Triangles Right Obtuse Acute Scalene Isosceles Equilateral Sum of internal angles Perimeter Area

22. Right If the largest measure of the triangle is 90 degrees

23. Obtuse When the largest angle of the triangle is more than 90 degrees

24. Acute When the largest angle of the triangle is less than 90 degrees

25. Scalene When all the sides of the triangle are not equal

26. Isosceles When there are two sides of the triangle that are the same measure

27. Equilateral When all the sides of the triangle have the same measure

28. Sum of internal angles All the sides in the triangle add up to 180 degrees 60 60 60

29. Perimeter The sum of all the sides of the triangle 50 70 60 50+70+60=180

30. Area When you multiply length times width and then divide it by 1/2. 30 60 60 times 30 divided by 1/2

31. Quadrilaterals Quadrilaterals Trapezoid Parallelogram Rectangle Rhombus Square Area of a rectangle Area of a square Area of a parallelogram Area of a trapezoid

32. Trapezoid A figure that has 1 set of parallel sides.

33. Parallelogram A figure that has 2 sets of parallel sides

34. Rectangle A figure that has 2 parallel sides and all the angles are congruent

35. Rhombus A parallelogram that has no congruent sides

36. Square A parallelogram that has 2 parallel sides and all the angles are congruent

37. Area of a rectangle You multiply length times width L W L times W= A

38. Square You multiply length times width L W L times W = A

39. Area of a Parallelogram You multiply length times width 8 12 8 times 12= A

40. Area of a Trapezoid You put 2 trapezoids together to make a rectangle and ad the top to the bottom then multiply it to width and divide by 2. W L 4+ 6= 10 divided by 2 4

41. Circles Chord Diameter Arc Radius Sector Circumference Area of a Circle

42. Chord The chord is the longest line segment in the circle

43. Diameter The diameter is the radius times 2

44. Arc The arc is the distance on the outside edge of the circle

45. Radius The radius is diameter divided by 2

46. Sector The sector is a piece of the area.

47. Circumference The distance around the circle (C= D times 3.14)

48. Other Polygons Hexagon Octagon Pentagon

49. Hexagon The hexagon is a polygon with six sides

50. Octagon The octagon is a polygon with eight sides

51. Pentagon The pentagon is a polygon with five sides

52. The End