Circle Graph

A circle graph is a graph that is represents data using sections of a circle.
Sector- A sector of a circle formed by 2 radii and the arc of the circle connection the 2 radii.




Example of a General Graph and a more Specific Graph



How many were asked ?


1) Title = Pets of students in Mr.W's class (24 students)
2) What are the different categories represented by the graph ?
- Cat, Dog, Other, No pets .
3) What percent of the class has a dog ? How many have a dog ?
- 25 % of the class has a dog .
- 6 kids have a dog
4) What percent of the class has a cat ? How many have a cat ?
- 33 % of the class has a cat .
- 1/3 of 24 = 8 Kids have a cat .
5) What percent of the circle is represented by all the sectors ?
- 100 %
6) Would this graph make sense if the title or sector labels were missing ?
- No, because then we wouldn't understand what the graph is all about .

Create your own Circle Graph on : http://www.mathplayground.com/piechart.html
Watch a video about circle graphs : http://www.youtube.com/watch?v=jFg-e51Rhv4

www.mathplayground.com

Circle

Parts of the Circle

• centre
• radius
• diameter
• circumference - is the distance around a circle
  

-usually represented by c

-this is a linear measurement

π = pi- the ratio of the circumference of a circle to its diameter

1. Find circumference if diameter is 2m.

2. Find circumference of each circle.

Circles

Radius - a distance from the centre of the circle to the outside edge.

- represented by r

Diameter - distance across a circle through its centre

- represented by d

A diameter is 2 radii.

Construct a circle with a radius of 4cm.

1. Start with centre of a circle.

2. Measure the length of a radius on a string.

3. Pencil at one end of string and pin the string in the centre of the circle.

4. Trace an arc around the centre.

Using a compass:

1. Measure a line the length of a radius.

2. Sharp point of compass in the centre of the circle.

3. Pencil at the other end of the line.

4. Draw an arc around the centre.

Homework:

pages 270-272

# 1-15

Do literacy link also.

Video/s and Link/s

Radius and Diameter

Definition of a Circle

Radius and Diameter (Video)

Today at school :)

Homework : 260- 261 (Chapter Review)
And 262- 263 ( Practice Test )
Remember : NO SCHOOL ON MONDAY :)

Subtracting with mixed numbers

If you have unlike denominators :
2 3/4 - 1 1/4
One method use fraction strips
* Second method = Subtract whole numbers
Answer the following :
a) 2 2/3 - 1 1/3 =
2 - 1 = 1
2/3 - 1/3 = 1/3
1 1/3

b) 3 7/8 - 1 3/8 =
3 - 1 = 2
7/8 - 3/8 = 4/8
2 4/8
Lowest terms = 2 2/4, 2 1/2

c) 4 3/4 - 1/4 =
3/4 - 1/4= 2/4
4 2/4
Lowest terms - 4 1/2

Unlike Denominators
- Find the common denominator
We don't want to have a whole number (2) and a negative fraction so we must regroup





* ANOTHER WAY TO REGROUP




Steps :
1. Subtract the whole numbers
2. Subtract fractions
3. Combine them


Answer the following ; a ) 4 1/4 - 3 2/5



b) 4 1/4 - 7/8

Subtracting Fractions With Unlike Denominators

To subtract fractions with unlike denominators, you MUST find a common denominator and use equivalent fractions.

eg. 3/4 - 1/2
eg.2/3 - 1/4

eg. 3/4 - 1/8

Unit Fraction- A fraction with a numerator of 1.

Do page 241- 244 # 1-23 odd THEN even.

• Do the odd numbers for homework.

Adding Fractions With Unlike Denominator

Adding Fractions With Unlike Denominator;

We must find a common denominator

- A multiple of the denominators of a set of fractions.

eg. a common denominator for 1/4 and 1/6 is 12 because a common multiple of 4 and 6 is 12

eg. x3 1/2 1/3 x2

x3 3/6 2/6 x2

3/6 + 2/6 = 5/6

Homework:

pages: 234-236

4-21 odds then evens.

heres a link that might help you out

http://www.helpwithfractions.com/adding-fractions-different-denominators.html