Area

Area - The space a shape takes up.
- Describe in square units 4cm2.

Review
Area of square or rectangle.









eg.










A = L x W
A = 6 x 2
A = 12cm2

Parallelogram:














eg.










A = bxh
A = 10 x 5
A = 50cm2

Finding Area of a circle.
Use pieces of circle to create to
a shape very close to a parallelogram.








Close to parallelogram.
h = radius of a circle
b = 1/2 circumference
Ap = b x h
Ao = 2 pi r/2 x r
Ao = pi x r x r
Ao = pi r 2

Find the area of a circle with a radius of 10m. Formula and work.
Ao = pi r 2
Ao = 3.14 x 10 2
Ao = 3.14 x 100
Ao = 314 m2

Find Area of following circles.








Answer for "8 cm":
Ao = pi r 2
Ao = 3.14 x 8 2
Ao = 3.14 x 64
Ao = 200.96cm 2

Answer for "14.8m":
Ao = pi r 2
Ao = 3.14 x 14.5 2
Ao = 3.14 x 219.64
Ao = 687.79cm 2









Answer for "6.8 m":
r = d/2
r = 6.8/2
r = 3.4

Ao = pi r 2
Ao = 3.14 x 3.4 2
Ao = 3.14 x 11.56
Ao = 36.30m 2

Answer for "20 cm":
r = d/2
r = 20/2

Ao = pi x 2
Ao = 3.14 x 10 2
Ao = 3.14 x 100
Ao = 314cm 2

Click here to check out this site.

Enjoy the video:

Wednesday March 16 Blog

Parts of a Circle :

• Radius
• Diameter
• Center
• Circumference : The distance around a circle, usually presented as a C.

This is a linear measurement :

Pi : is the ratio of the circumference of a circle to its diameter.
Pi = C/D, where C = circumference and D = diameter
Pi is approximately 3.14


Formulas:
Pi = C/D
C = Pi x D
D = C/Pi
D = 2(r)


Questions:

Find the circumference of each circle. Use the formulas above to answer the question.





















1. C = Pi x D
= 3.14 x 40
= 125.6 mm

2. C = Pi x 2(r)
= 3.14 x 2(16.8)
= 3.14 x 33.6
= 105.504 cm

3. C = Pi x D
= 3.14 x 12.6
= 39.6 m

4. C = Pi x 2(r)
= 3.14 x 2(32.6)
= 3.14 x 65.2
= 204.728 m

Check out this website

Circles

Radius - distance from the center of the circle to the outside edge .

- represented by r



Diameter - is a 2 radii .

d = 2r

r = 9/2



Construct a circle with a radius of 4cm using a string .



1. Start with the center of the circle .
2. Measure the length of the radius on a string .
3. Use the Pencil at the end of the string and join the string
to the circle .
4. trace an ark around around the center.


Another way:


Use a compass


1. Measure a line of the length.
2. Pencil the other length of the line.
3. Draw an ark around the center.


Homework: Page 270 - 272
number 1 - 15
+ literacy link.



http://youtube.com/watch?v=s0xJNGwljbY

Sorry the video is a website . It didn't work when I post it .

Subtracting Mixed Numbers

If you have like denominators:

2 3/4 - 1 1/4= -use fraction strips!



take away - You are left with:

Write in lowest terms:

Here are the steps:
1- subtract whole numbers
2- subtract fractions
3- write in lowest terms

So the answer is: 2 3/4 - 1 1/4= 1 2/4-- in lowest terms 1 1/2

Click here to go to a website on subtracting mixed numbers

Adding Mixed Numbers

On Monday, we learned how to add mixed numbers.

A situation that was given to us was:
On Pizza day, 1 5/6 of cheese pizza, and 1 5/6 of bacon pizza were left. How many altogether?


Steps:
1) Add whole numbers.
2) Find a common denominator for fractions.
3) Add fractions.
4) Add whole numbers to fractions.


This is the situation changed into a mathematical equation:
1 + 1 + 5/6 + 5/6 =

How to solve it:

2 + 5/6 + 5/6 =
2 + 10/6 =
2 + 6/6 + 4/6 =
2 + 1 + 4/6 =
3 4/6 =
3 2/3

The answer is 3 2/3.

Another way to add mixed numbers is using a diagram.


Take one from the last one to make the second 1 whole. That gives us 3 wholes and 4/6 in lowest terms is 2/3.




We did some practice with adding mixed numbers:

Like-denominators:
a) 1 1/3 + 2 1/3 =
3 + 1/3 + 1/3 =
3 + 2/3 =
3 2/3

b) 3 1/6 + 2 5/6 =
5 + 1/6 + 5/6 =
5 + 6/6 =
5 + 1 =
6

c) 3 2/3 + 2/3 =
3 + 4/3 =
3 + 1 + 1/3 =
4 + 1/3 =
4 1/3


Unlike-denominators:
a) 1 1/2 + 2 1/3 =
6 + 1/2 + 1/6 =
6 + 4/6 =
6 4/6 =
6 2/3

b) 2 1/2 + 4 1/6 =
6 + 1/2 + 1/6 =
6 + 4/6 =
6 4/6 =
6 2/3

c) 3 3/5 + 1/2 =
3 + 11/10 =
3 + 1 + 1/10 =
4 + 1/10 =
4 1/10

Mixed numbers can be expressed in 4 ways: 1 1/2, 1.5, One and one half, 1 + 1/2.

Here is a great website for adding mixed numbers!

The video shown here helps you understand more about adding mixed numbers with unlike denominators:

Make sure to leave a comment!

Adding Mixed Numbers

Cheese Pizza: 6/6=1 + 5/6 = 1 5/6 Bacon Pizza : 6/6=1 + 5/6 =1 5/6

Here are some steps to add mixed numbers:

1 5/6+1 5/6=

1+1=2 1st- Add the whole numbers.

5/6+ 5/6= 10/6 <-- this is 1 whole and 4/6 2nd- Find a common denominator for the fractions.

2+ 1=3 3rd- Add the fractions.

3+ 4/6= 3 4/6 4th- Add the whole bumbers to the fraction.

Lowest term would be 3 2/3 5th- Add up the whole number and the fraction.

Here is another way to add mixed fractions:

1st- Take 1 from the last fraction to make the second fraction one whole.

2nd- Then just add up. So it should look like this:

Here's a video about adding mixed numbers
Click here to go to a good site all about adding mixed numbers

Subtracting Fractions with Unlike Denominators

You must find a common denominator
and use an eqivalent fraction.

Examples.
3/4 - 1/2 = ?


4-4,8,12,16

4 is their common denominator.
2-2,4,6,8,



So you change 1/2 into 2/4 since what ever you do to the bottom u do to number.

3/4 - 2/4 = 1/4

(More examples)
2/3 - 1/4 = 8/12 - 3/12
5/12

3/4 - 1/8 = 6/8 - 1/8
5/8

Here's a link and video to help you.

http://www.aaamath.com/fra66lx2.htm link

http://www.youtube.com/watch?v=T8Lo_cOW0As video

Unit fraction
A fraction with a numerator of 1.
Examples.
1/2, 1/3, 1/4, 1/10, 1/100, 1/anything.


Homework: pg 241-244.

Adding Fractions with Unlike Denominator

1/2 + 1/3=?

This is just like adding to fruits together

1 apple+ 1 orange= 2 fruits

To answer the question on top of the page we must find Common Denominator!

A multiple of the denominators of a set of Fractions.

Example: A common denominator for 1/4 and 1/6 is 12 because a common multiple of 4 and 6 is 12.

4- 4,8,12,16

6- 6,12,18,24

1/2 + 1/3

X2

3/6 + 2/6

You can also Cross Multiply!

1 - 4

_ X_ They should all be equal together

3 - 12

Here is a link I found for you guys to learn more about adding fractions with unlike denominators

http://staff.argyll.epsb.ca/jreed/math8/strand1/1203.htm

Here is the video for this subject because it took too long just to upload!
http://www.youtube.com/watch?v=MEo0rSZ4O3w&feature=fvw