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## For this topic you will need to know:

## Equilateral, Isosceles and Scalene Triangles:

There are three special names given to triangles that tell how many sides (or angles) are equal.There can be

3,2ornoequal sides/angles:## Equilateral Triangle

Threeequal sidesThreeequal angles, always 60°## Isosceles Triangle

Twoequal sidesTwoequal angles## Scalene Triangle

Noequal sidesNoequal angles## What Type of Angle?

## As the Angle Increases, the Name Changes:

less than 180°

## Combining the Names

Sometimes a triangle will have two names, for example:## Right Isosceles Triangle

Has a right angle (90°), and also two equal anglesCan you guess what the equal angles are?

## You might also like to play with the Interactive Triangle.

## Try working out angles in a triangle in this worksheetAngles in a triangle sheet (basic).pdf

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## or harderAngles in a triangle sheet.pdf

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- 42 KB

## Quadrilaterals

(

quadmeans four,lateralmeans side).Any four-sided shape is a Quadrilateral.But the sides have to be

straight, and it has to be2-dimensional.## Try for Yourself

(You can also play with Interactive Quadrilaterals)

## Properties

360 degrees:360°## Try to work out the unknown angles of the quadrilaterals in this worksheet:Angles in a quadrilateral worksheet.pdf

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## Types of Quadrilaterals

There are special types of quadrilateral:

Some types are also included in the definition of other types! For example a

square,rhombusandrectangleare also. See below for more details.parallelogramsLet us look at each type in turn:

## The Rectangle

means "right angle"show equal sidesAlso

opposite sidesare parallel and of equal length.## The Rhombus

Also opposite sides are parallel

andopposite angles are equal.Another interesting thing is that the diagonals (dashed lines in second figure) meet in the middle at a right angle. In other words they "bisect" (cut in half) each other at right angles.

A rhombus is sometimes called a diamond.

## The Square

means "right angle"show equal sidesAlso opposite sides are parallel.

A square also fits the definition of a

rectangle(all angles are 90°), and arhombus(all sides are equal length).## The Parallelogram

## Example:

parallelogramwith:- all sides equal and
- angles "a" and "b" as right angles

is asquare!## The Trapezoid (UK: Trapezium)

It is called an

Isoscelestrapezoid if the sides that aren't parallel are equal in length and both angles coming from a parallel side are equal, as shown.And a

trapezium(UK: trapezoid) is a quadrilateral with NO parallel sides:## The Kite

... and that's it for the special quadrilaterals.

## Irregular Quadrilaterals

The only regular quadrilateral is a square. So all other quadrilaterals areirregular.## The "Family Tree" Chart

Quadrilateral definitions areinclusive.## Example: a square is also a rectangle.

So weincludea square in the definition of a rectangle.(Wedon'tsay "Having all 90° angles makes it a rectangle except when all sides are equal then it is a square.")This may seem odd, as in daily life we think of a square as

notbeing a rectangle ... but in mathematics itis.Using the chart below you can answer such questions as:

## Complex Quadrilaterals

Oh Yes! when two sides cross over, you call it a "Complex" or "Self-Intersecting" quadrilateral like these:## Polygon

A quadrilateral is a polygon. In fact it is a 4-sided polygon, just like a triangle is a 3-sided polygon, a pentagon is a 5-sided polygon, and so on.## Play with Them

Now that you know the different types, you can play with the Interactive Quadrilaterals.## Other Names

A quadrilateral can sometimes be called:Quadrangle("four angles"), so it sounds like "triangle"Tetragon("fourandpolygon"), so it sounds like "pentagon", "hexagon", etc.PolygonsIrregular polygons are where not all the sides (and angles) are the same.

## 3D Shapes

Here are some notes about adding angles in a triangle

Adding angles in a triangle.pdf

## Angles On One Side of A Straight Line

## Angles on one side of a straight line will always add to

If a line is split into 2 and you know one angle you can always find the other one.180 degrees.30° + 150° =

180°## Example: If we know one angle is 45° what is angle

"a"?ais 180° − 45° =135°This method can be used for several angles on one side of a straight line.

## Example: What is angle

==||"b"?bis simply 180° less the sum of the other angles.Sum of known angles = 45° + 39° + 24° Sum of known angles = 108°

Angle

b## 180° − 108°Angle

72°bClick on this link for more examples and gamesOr this link to check out 'Angles at a Point'Compass: North, South, East and West

Directions on the "Compass Rose"

## Compass Bearings

A Compass Bearing tells usDirection

The 4 main directions are

North,South,EastandWest(going clockwise they are NESW).How to remember?With North pointing ahead, "West" and "East" make the word "WE"

## Play The Game

Try the Direction Game.## In Between

Halfway between North and East is North-East (NE).There is also South-East (SE), South-West (SW) and North-West (NW).

And in between all of those are:

Example: in the morning there was a strong North wind, but later it swung around to the North-East

Example: they were sailing mainly South-West, but sometimes a little towards South-South-West.

## Three-Figure Bearings

Three-figure bearings are an alternative to compass bearings that are much more precise. They are measured in a special way:- Start measuring from the direction North
- Measure clockwise
- Give the bearing using three figures (or more than three if there's a decimal)

Airline pilots and ships' helmsmen use three-figure bearings so that they can point their craft in exactly the right direction to safely reach their destination.## Examples

The four main compass bearings (North, East, South and West) are multiples of 90°:Notice that east, for example is 090° rather than 90° because it is given as three figures.

The advantage of three-figure bearings is that they describe any direction uniquely:

Note that the last one has four figures (three in front of the decimal point and one after) but it is still a "three-figure bearing", the .4 just gives more accuracy.

Example: South-West is 225 (in other words 225° clockwise from North)

Activity: A Walk in the Desert

2Measurement Index

Check out this site for notes and examples on bearings## Bearing lesson:

Try the questions on this linkSee if you can help this person find the answer he is looking for - you will need to read this carefully

Now do the 'bearing' worksheet

## Transformation lesson:

Read about transformations hereNow read and do the lessons on Rotation

Read and do the lessons on Reflection

Read and do the lessons on Translation

Read and do the lessons on Resizing

HOLIDAY TASK: Create a tessellation (due on your first day back from holiday)## Below are a couple of examples; they look like wall paper patterns, you can use polygons (shapes with straight sides) or other shapes. You can find more shapes by 'googling' Tessellations and selecting 'images'. This website shows you how to create your own tessellation. So does this one. You can find your own websites too :)

## Here is a youtube video on how to make a tessellation.