GEOMETRYSHAPES

TRIANGLE

TRIANGLE – 3 SIDED SHAPE TRI MEANS 3

TRIcycle (3 wheels)

TRIlogy (3 books in the series)

(3 Horns)

QUADRILATERAL

A quadrilateral is a polygon with 4 sides. These are all quadrilaterals:

“QUAD” MEANS 4

Quadriceps – 4 muscles

Quadrant – 4 sections

Quadruplets (4 babies)

PENTAGON

•A pentagon is a 5-sided shape.•“Pent” means 5

U.S. Pentagon in Washington D.C.

Pentagram – 5 pointed star

HEXAGON

•A hexagon is a 6-sided shape•“Hex” means 6

Hexagram – 6-pointed star

HEX nut – six sided nut

(Ask Jacob)

Hexapod – 6 feet

HEPTAGON

•A heptagon is a 7-sided figure•“Hept” means 7

Heptathlon – 7 event competition Heptadactyly– 7 fingers on 1

hand

OCTAGON•An octagon is an 8 sided figure•“Octa” means 8

Octopus – 8 legs

Octamom!

Octogenarian – a person who is in there 80’s

NONAGON

•A nonagon is a 9-sided figure•From the Latin word “nonus” and the Greek word enneagonon, meaning 9

Enneagram – 9 personality types

DECAGON

•A decagon is a 10-sided shaped•“Deca” means 10

Decathalon – 10 track and field

events

Decade – 10 years

Decimal – base 10 number system

LET’S REVIEW

PENTAGON

heptagon

HEXAGON

NONAGON

OCTAGON

DECAGON

CLASSIFYING QUADRILATERALS

Quadrilateral – 4 sides, 4 angles, a type of polygon

Rectangle – opposite sides are congruent; has 4 right angles

Square – 4 congruent sides; 4 right angles

Parallelogram – opposite sides are congruent and parallel

Rhombus – 4 congruent sides; opposite sides are parallel

Trapezoid – only 1 pair of parallel sides

LET’S CLASSIFY

Polygon

Polygon

Quadrilateral Trapezoid

Quadrilateral

Parallelogram

LET’S CLASSIFY

Polygon Quadrilater

al ParallelogramRhombus

PolygonQuadrilater

al ParallelogramRhombus

RectangleSquare!

TRIANGLES

A triangle has 3 sides and 3 angles

TYPES OF TRIANGLES BASED ON HOW MANY SIDES AND ANGLES ARE EQUAL

An EQUILATERAL triangle has 3 equal sides and 3 equal angles (always 60 degrees)

An ISOSCELES triangle has 2 equal sides and 2 equal angles

An SCALENE triangle has NO equal sides and NO equal angles

TYPES OF TRIANGLES BASED ON TYPES OF ANGLES

An ACUTE triangle is a triangle with ALL angles less than 90 degrees.

A RIGHT triangle is a triangle with a 90 degree angle.

An OBTUSE triangle is a triangle with an angle of more than 90 degrees.

A TRIANGLE CAN HAVE TWO NAMES

isosceles right triangle

TRIANGLES

An equilateral triangle is always….ACUT

E

TRIANGLES

In a right triangle, one of the angles is a right angle—an angle of 90 degrees. A right triangle may be isosceles or scalene.

In an obtuse triangle, one angle is greater than a right angle—it is more than 90 degrees. An obtuse triangle may be isosceles or scalene.

In an acute triangle, all angles are less than right angles—each one is less than 90 degrees. An acute triangle may be equilateral, isosceles, or scalene.

YOUR TURN!

Draw each of the following:

1.Right isosceles triangle2.Obtuse scalene triangle3.An acute equilateral triangle

1.Right isosceles triangle

2. Obtuse scalene triangle

3. Acute equilateral triangles