Geometry For Dummies

LinesAnglesTriangleQuadrilateralCirclesOther Polygons

Lines

Points

Lines segments

Rays

Lines

Intersecting Lines

Perpendicular Lines

Paraell lines

Ray

A point where the ray starts at one location and never end.

Points

A Point is a precise location with a letter

Fontwork

Point A

Point B

Planes

A surface containing all the straight lines that connect any two points on it

B

Line Segment

A straight line that can be measured

B

C

Line Segment

A straight line that can be measured

B

C

Line

A line that never ends

Properties of Lines

Intersecting

Perpendicular

Skew

Parallel

Intersecting Lines

Cross at a point

Perpendicular Line

Intersect at right angle 90 degrees

Skew

Lines that aren't at the same place.

Parallel

Line that never cross and are at the same place.

Angles

Right AnglesObtuse AnglesAcute Angles

Right Angles

An angle that is 90 degrees.

Obtuse Angles

An angle that is more that 90 degrees.

180

Acute Angles

An angle that is less than 90 degrees.

80 degrees

Triangles

Equilateral TriangleIsosceles TriangleScalene TriangleAcute TriangleObtuse TriangleRight Triangle

Equilateral Triangle

A triangle having all three sides equal. The angles of an equilateral triangle all measure 60 degrees.

Isosceles Triangle

A triangle having two sides of equal length.

Scalene Triangle

A triangle having three sides of different lengths.

Acute Triangle

A triangle having three acute angles.

Obtuse Triangle

A triangle having an obtuse angle. One of the angles of the triangle measures more than 90 degrees.

Right Triangle

A triangle having a right angle. One of the angles of the triangle measures 90 degrees.

Quadrilaterals

Square RhombusTrapezoidParallelogramRectangle

Parallelogram

A polygon with four side and four angles

Trapezoid

A quadrilateral plane figure having two parallel and two nonparallel sides

Rectangle

A rectangle is a square but stretched out two sides are equal and the other are equal but a different size.

Rhombus

A rhombus is a square but tilted

Square

All sides congruent and both sides are parallel

Circles

ChordsDiameterArcRadiusSector CircumferenceArea of a Circle

Chords

Segment connecting two outside points on a circle.

E

J

EJ

Diameter

Longest chord on a circle; passes through the center of the circle.

T

E

TE

Arc

The portion of the circle

E

J

Radius

Half of the length of the diameter; runs from the center of the circle to its edge.

E

J

Sector

A slice of a circle's area, defined by two points on the outside boundaries. The vertex of the slice is the center of the circle.

E

F

Circumference

The distance around the outside of a circle; its perimeter.

3.14

Area of a Circle

The amount inside the circle.

Pie r2

Other Polygons

PentagonHexagonHeptagonOctagonNonagonOctagon

Pentagon

A five-sided polygon. The sum of the angles of a pentagon is 540 degrees.

Hexagon

A six-sided polygon. The sum of the angles of a hexagon is 720 degrees.

Heptagon

A seven-sided polygon. The sum of the angles of a heptagon is 900 degrees.

Octagon

An eight-sided polygon. The sum of the angles of an octagon is 1080 degrees.

Nonagon

A nine-sided polygon. The total of the angles of a nonagon is 1260 degrees.

Decagon

A ten-sided polygon. The sum of the angles of a decagon is 1440 degrees.

The Credits

Directed by: Emma JiaDesigned by: Emma JiaPictures from: http://www.flickr.comhttp://www.mathleague.comFrom: Room 15, Mr. Lindsay's class