GeometryLet’s do it!!

closed figure A figure that begins and ends at the same point

Examples:

                                 

area The number of square units needed to cover a surface

Example:                         The area is 9 square units.

congruent Having the same size and shape

Example:                                The triangles are congruent.

similar figures Figures with the same shape but not necessarily the same size

                                                     

polygon A closed plane figure formed by three or more line segments

Examples:                                                 

http://www.math.com/school/subject3/lessons/S3U2L1GL.html

• Polygons are many-sided figures, with sides that are line segments. Polygons are named according to the number of sides and angles they have. The most familiar polygons are the triangle, the rectangle, and the square. A regular polygon is one that has equal sides. Polygons also have diagonals, which are segments that join two vertices and are not sides.

Name Sides Angles

Triangle 3 3

Quadrilateral 4 4

Pentagon 5 5

Hexagon 6 6

Heptagon 7 7

Octagon 8 8

Nonagon 9 9

Decagon 10 10

hexagon A polygon with six sides and six angles Examples:

                                                

octagon A polygon with eight sides

Examples:

                                                

square A rectangle with 4 equal sides

Example:

                      

pentagon A polygon with five sides

Examples:

                                                   

pentagon A polygon with five sides

Examples:

                                                   

Quadrilateral

• A quadrilateral is a four-sided polygon with four angles. There are many kinds of quadrilaterals. The five most common types are the parallelogram, the rectangle, the square, the trapezoid, and the rhombus.

• http://www.math.com/school/subject3/lessons/S3U2L3GL.html

Identify the Triangles

• Triangles are classified according to the measures of their angles.

• Acute, right, obtuse

Right Triangle• A RIGHT triangle has ONE right angle.

obtuse triangle

A triangle that has one obtuse angle

Example:

                                                      

Obtuse Triangle• An OBTUSE triangle

has ONE obutse angle

acute triangle A triangle in which all three angles are acute

                                                           

Acute Triangle

• An ACUTE triangle has THREE acute angles.

Identify the Triangles

• Triangles are also classified according to their

length.

• Scalene Triangle- no congruent sides

• Isosceles Triangle- two congruent sides

• Equilateral Triangle- three congruent sides

angle A figure formed by two rays that have a common endpoint

Example:

                               

Angle

complementary angles Two angles whose measures have a sum of 90° Example:

                                                                            

• acute angle • An angle that has a measure less

than a right angle (less than 90°)

Example:                             

Acute Angle

• Acute Angles An ACUTE ANGLE is one whose measure is LESS THAN 90 DEGREES. Notice CAB does not quite reach 90 degrees... acute angles are always less than 90 degrees.

adjacent angles Angles that are side by side and have a common vertex and ray

                ABD is adjacent to   DBC.

Right Angle

• A RIGHT ANGLE is an angle whose measure is EXACTLY 90 DEGRRES. Right angles are denoted by a small square in its interior.

Obtuse Angle

• An OBTUSE ANGLE is one whose measure is GREATER THAN 90 AND LESS THAN 180 DEGREES.

Straight Angle

• A STRAIGHT ANGLE is one whose measure is EXACTLY 180 DEGREES.  A straight angle is made up of two opposite rays.   Another important fact is that a straight angle forms a straight line. 

Reflex Angle

• A REFLEX ANGLE is one whose measure is GREATER THAN 180 AND LESS THAN 360 DEGREES.

CONGRUENT ANGLES -

• Two angles that have the same measure are called Congruent Angles.  Equal measure angles are labeled as shown in the diagram.

VERTEX -

• The common point for both rays is called the Vertex. 

• A POINT is one of the basic UNDEFINED terms of geometry.  Points have no length, width, or thickness and we often use a dot to represent it. The diagram gives examples of some of the possible INTERPRETATIONS or MODELS of what a point could look like.

LINE

• A LINE is one of the basic UNDEFINED terms of geometry.  A line has no thickness but its length goes on forever in two directions. The arrows represent the fact that the line extends in both directions forever.

Lines

• A line is one of the basic terms in geometry. We may think of a line as a "straight" line that we might draw with a ruler on a piece of paper, except that in geometry, a line extends forever in both directions. We write the name of a line passing through two different points A and B as "line AB" or as , the two-headed arrow over AB signifying a line passing through points A and B.

• Example: The following is a diagram of two lines: line AB and line HG.

PLANE

• SPACE is the boundless, three-dimensional set of all points.  Thus planes, lines and points are contained in space.  A third basic geometric figure is a PLANE.

• translation (slide)

• A movement of a figure along a straight line