Geometry Vocabulary Part One

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

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

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.” The corners of a square are its vertices. When two lines cross, they form vertices.

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

SIMILAR Similar shapes have corresponding sides that are in proportion to each other. Similar shapes have EQUAL corresponding angles. 10 feet4 feet 5 feet2 feet

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

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

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.

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. CLOSEDOPEN ● ● ● Start End Start End

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. POLYGON NOT POLYGON

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

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

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

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.

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

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

ACUTE ANGLES are less than 90°.

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

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

STRAIGHT ANGLE is exactly 180 °.

NAMING ANGLES When you “name” an angle, the vertex/angle “letter/number” goes in the center of the label. A B 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)

Complementary Angles Add up to 90 degrees

Supplementary Angles Add up to 180 degrees

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).

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

INTERIOR INSIDE Angle LGH is an interior angle.

EXTERIOR OUTSIDE This exterior angle is 270 degrees.

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

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

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