Geometry Vocabulary

1. Geometry Vocabulary Part One

2. POINT • A POINT is an exact location on a graph, shape or in “space”. • The Hershey Kiss is a POINT on the line. ●

3. LINE • A LINE goes in opposite directions and never, never, never ends. Imagine if this Twizzler went on forever and ever and ever and ever and ever and ever

4. VERTEX • A VERTEX is a fancy name for “angle.” • Two rays or lines that have the same endpoint make a VERTEX/angle. • VERTICES/angles are measured in “degrees.” When two lines cross, they form vertices. The corners of a square are its vertices.

5. CONGRUENT • CONGRUENT means the “same.” • CONGRUENT LINE SEGMENTS means two line segments are the same. • CONGRUENT Vertices/Angles means two angles are the same. ● ● ● ● The Hershey & Crunch Bar are a Congruent size

6. SIMILAR • Similar shapes have corresponding sides that are in proportion to each other. • Similar shapes have EQUAL corresponding angles. 10 feet 4 feet 5 feet 2 feet

7. VERTICAL LINE • A VERTICAL LINE goes up & down. The candy bars are vertical

8. HORIZONTAL LINE • A HORIZONTAL LINE goes “across” (left and right) The candy bars are Horizontal

9. PLANE • A PLANE (no, not the one that flies!) is a flat surface that goes on forever in all directions. • Imagine sitting on a row boat in the middle of the ocean. No matter which way you look…all you see is water…forever.

10. OPEN & CLOSED FIGURES • A CLOSED FIGURE/SHAPE starts and ends at the same point. • An OPEN FIGURE/SHAPE does NOT start and end at the same point. CLOSED OPEN Start Start ● ● ● End End

11. POLYGON • A POLYGON is a “closed” shape. • A POLYGON is made up of line segments that do not cross. • The number of sides gives a POLYGON its name. • Regular polygons have all equal sides and angles. NOT POLYGON POLYGON

12. TRIANGLES • Are polygons. • Have 3 sides. • Have 180 degrees. • Can be equilateral, isosceles, right, or scalene.

13. QUADRILATERALS • Are polygons. • Have 4 sides. • Have 360 degrees. • Can be a square, rectangle, parallelogram, rhombus, or trapezoid.

14. And it continues… • 5 sides = pentagon • 6 sides = hexagon • 7 sides = heptagon • 8 sides = octagon • 9 sides = nonagon • 10 sides = decagon • 11 sides = hendecagon • 12 sides = dodecagon

15. INTERSECTION • Where 2 objects cross. • If it forms a right angle, they are perpendicular. Ray A intersects the triangle in 2 points. A These rays are perpendicular.

16. OVERLAP • Where 2 shapes cross as if lying on top of one another. These shapes overlap, instead of lying flat.

17. PROTRACTOR • We use a PROTRACTOR to measure vertices/angles in degrees.

18. ACUTE ANGLES are less than 90°.

19. RIGHT ANGLES measure exactly 90 °. The “square” symbol means 90’

20. OBTUSE ANGLES are greater than 90 ° but less than 180 °.

21. STRAIGHT ANGLE is exactly 180 °.

22. NAMING ANGLES • When you “name” an angle, the vertex/angle “letter/number” goes in the center of the label. B A C If I wanted to know the measurement of Angle A…I would ask:” What is the measurement for BAC?” (Notice A is in the center)

23. Complementary Angles • Add up to 90 degrees 200 700

24. Supplementary Angles • Add up to 180 degrees 1500 300

25. Adjacent • Side by side, or touching A B F C E D Sides AB and BC are adjacent, because they share a common point (B).

26. Corresponding • Relates to or goes with A B F C E D Side AB corresponds to side GH. G H L I K J

27. INTERIOR • INSIDE Angle LGH is an interior angle.

28. EXTERIOR • OUTSIDE This exterior angle is 270 degrees.

29. PERIMETER • The sum of the side lengths of any figure. Perimeter = 14 5 long 2 wide 2 wide 5 long

30. AREA • The amount of surface covered by a shape. Area = 10 units 2 5 long 2 wide 2 wide 5 long

31. The End • Once you study all the “fancy words”, Geometry is very easy to understand…so STUDY!