Geometry Vocabulary 7-1 By: Hilary Clinger & Alex Shipherd

Point An exact location in a space Represented by a dot Named by a capital letter A

Line A collection of points along a straight path extending forever in opposite directions Draw a line with arrows on both ends Named by any to points on the line in either order K J L

Line Segment Part of a line with two endpoints, it has both a beginning and an end It can be measured, using a ruler Drawn as a line with no arrows Named by the two endpoints, in either order P O

Endpoint Where a ray begins Endpoint

Ray Part of a line that extends forever in only one direction Where it begins is called the endpoint Drawn as a line with only on arrow Named by the endpoint and any other point on the ray, endpoint always comes first

Plane A flat surface that extends in all directions forever Anything than can be drawn in a plane is called a plane figure Named by three points in the plane

Intersecting Lines Intersect or meet at one point D C B A F

Parallel Lines Do not intersect anywhere, where they remain

Perpendicular Lines A special kind of intersecting lines form right angles at the point of intersection.

Concurrent Lines Intersect everywhere one line lays on top of the other lines

Angle An angle is formed by two rays that have a common endpoint called the vertex The rays are the sides of the angle Drawn with two rays

Angles (continued) Named by three points one on each ray and the vertex is always in the middle Or named by the vertex Or named by a number We can measure an angle in degrees using a protractor

Acute Angle Measures between 0° and 90° Right Angle Obtuse Angle Straight Angle Measures exactly 90° Measures between 90° and 108° Measures exactly 180°

Protractor A protractor is used to measure angles You can draw angles by using protractors How to use a Protractor: Step 1: Center the protractor on the vertex of the angle Step 2: Align the 0° mark on one side of the angle Step 3: Read the measure where the other side passes through the protractor

Supplementary Angles Two angles whose sum of their measures is equal to 90° are complementary angles Complementary Angles Two angles whose sum of their measures is equal to 180° are supplementary angles 1 2 m 1+m 2= 90° m 3+m 4= 180° 34

Adjacent Angles Vertical Angles Share the common vertex and a common side Share only the common vertex. The measures of the vertical angles are equal C D E F G 120° 60° Think: m EDG = m CGF m CGE = m FGD J A L M Think: JAL is adjacent to LAM

Transversal Two pairs of parallel lines are both intersected by a third line, several pairs of congruent angles are formed. At each point of intersection two pairs of vertical angles are formed

Corresponding Angles Are congruent m 1= m 5 m 2= m 6 m 3= m 7 m 4= m 8

Alternate Interior Angles The measure of the angles on opposite sides of the transversal both inside and outside the parallel lines are equal. Alternate Exterior Angles The measure of the angles on opposite sides of the transversal both inside and outside the parallel lines are equal

Triangle Polygon with 3 sides, angles, and vertices. Different sizes and shapes Classified according to the length of their sides or according to the measure of their angles

Acute Triangle Three acute angles

Right Triangle One 90° angle Two acute angles (less than 90°)

Obtuse Triangle One obtuse angle Two acute angles

Scalene Triangle No congruent sides No congruent angles

Isosceles Triangle Two congruent sides Two congruent angles

Equilateral Triangle Three congruent sides Three congruent angles

Reflection A flip

Line of Symmetry When you can fold a shape and have it match perfectly with itself A heart has one line of symmetry. A square has four.

Dilation To dilate a polygon, multiply the coordinates of each vertex by the scale factor and connect the vertices.

Image The shape after it has been reflected Image

Rotation When you turn a shape

Transformation Moving a shape but not changing it

Translation When you slide a shape

The rest of the vocabulary is on our wikis. Geometry List Vocabulary 7-1 By: Hilary Clinger and Alex Shipherd