Download GEOMETRY REVIEW BASIC VOCABULARY Point

GEOMETRY REVIEW
BASIC VOCABULARY
Point - an exact location in space-- usually labeled with a capital letter.
Ex: • P
Line - a set of points in a straight path which extend infinitely in both directions -- named by choosing 2
vertices.
Ex:
Ray - a part of a line with one endpoint (extends infinitely in one direction).
Ex:
Line Segment - a part of a line with two endpoints.
Ex:
Plane - a flat surface which extends infinitely in all directions. You need 3 points to determine a plane.
Ex:
Perpendicular Lines - two lines that intersect to form right angles.
Ex:
Parallel Lines - two lines in the same plane that never intersect and are always the same distance apart.
Ex:
Skew Lines - two lines in different planes that never intersect
ANGLES
Angle - two rays with a common endpoint (vertex).
Ex:
Acute angle - an angle that measures less than 90 degrees.
Ex:
Right angle - an angle that measures exactly 90 degrees.
Ex:
Obtuse angle - an angle that measures greater than 90 degrees but less than 180 degrees.
Ex:
Straight angle - an angle whose measure is exactly 180 degrees.
Ex:
Reflex angle - an angle whose measure is greater than 180 degrees but less than 360.
Ex:
CLASSIFYING TRIANGLES
…according to the size of the angles
Acute Triangle – a triangle with three acute angles.
Ex:
Right Triangle – a triangle with one right angle (and two acute angles).
Ex:
Obtuse Triangle – a triangle with one obtuse angle (and two acute angles).
Ex:
…according to the length of the sides
Scalene Triangle – a triangle with no sides the same length.
Ex:
Isosceles Triangle – a triangle with two sides congruent
Ex:
Equilateral Triangle – a triangle with three sides congruent. Each angle measures 60 degrees.
Ex:
POLYGONS
Polygon – a simple closed figure made up of three or more line segments.
Polygons are classified by the number of sides. See chart below:
# sides
Polygon
SUM of the
angles
(in degrees)
3
Triangle
180
4
Quadrilateral
360
5
Pentagon
540
6
Hexagon
720
7
Heptagon
900
8
Octagon
1080
9
Nonagon
1260
10
Decagon
1440
11
Undecagon
1620
12
Dodecagon
1800
Total amount of degrees = 180(#of sides – 2)
Convex
Concave
Regular Polygon – a polygon with all sides congruent and all angles the same measure.
Ex:
Diagonal – a line segment which connects any two non-consecutive vertices of a polygon.
Ex:
Circle – a set of points equally distant from a given point called the center.
PARTS OF A CIRCLE
Radius
Diameter
Chord
Tangent Line
Secant Line
Central Angle
Arc
Complementary Angles – two angles that have a sum of 90 degrees.
Supplementary Angles – two angles that have a sum of 180 degrees.
Transversal – a line that intersects two or more other lines
Vertical Angles – angles which are directly opposite each other at an intersection.
Corresponding Angles – angles which lie in the same position in both intersections.
Alternate Interior Angles – angles which are on opposite sides of the transversal and INSIDE the parallel
lines.
Alternate Exterior Angles – angles which are on opposite sides of the transversal and OUTSIDE the
parallel lines.