We think you have liked this presentation. If you wish to download it, please recommend it to your friends in any social system. Share buttons are a little bit lower. Thank you!
Presentation is loading. Please wait.
Published byAutumn Rowe
Modified over 2 years ago
How to calculate the area of a circle. Its as easy as pi.
Lets first make sure that we understand the difference between circumference and area.
The circumference of a circle is the perimeter of the circle.
Imagine that the circle is straightening itself out.
The length of this line segment is the circumference of the circle. 314 cm
The circumference is the same length as 3 diameters plus.14 of another diameter.
So, circumference = diameter x 3.14
Does this look familiar?
O.K., now its time to move forward with some new stuff.
How in the world would you find the area of a circle?
Remember, area is always measured in square units.
Remember that the area of a rectangle is length x width because youre calculating the total number of squares inside of the rectangle. 2 4
Thats fine and dandy, but a circle is not a polygon. It does not have straight sides; it has curves.
How are we going to get around these curves?
Imagine chopping up the circle as if it were a pizza.
Now, lets rearrange our pizza into another shape.
Great Mr. Dunlap! But what in the world is this?
Believe it or not, this is really our friend the parallelogram. And, we know how to calculate the area of a parallelogram.
Rats! He always has an answer for everything.
Area = Base x Height Base Height
To find the area of the circle (which is now a parallelogram), we just need to multiply the Base by the Height. Base Height
Base Radius Wait a minute! The height of this parallelogram is really the radius of the circle.
1/2 of Circumference Radius Wait a minute! The Base is really 1/2 of the circumference.
1/2 of Diameter x Radius Wait a minute! The circumference is really Diameter x
Radius x Radius Wait a minute! 1/2 of a Diameter is really a Radius.
Base Height So if we multiply the Base x Height
We are really multiplying Radius x Radius x Radius x Radius
1) Now lets try this formula. Find the area of this circle. 5 cm
5 x 5 x 3.14 = 78.5 square cm 5 cm
2) Find the area of this circle. 6 cm
6 x 6 x 3.14 = square cm 6 cm
3) Find the area of this circle. 9 cm
9 x 9 x 3.14 = square cm 9 cm
4) Find the area of this circle. 20 cm
10 x 10 x 3.14 = 314 cm 2 20 cm Make sure that you use the radius of the circle.
5) Find the area of this circle. 14 cm
7 x 7 x 3.14 = cm 2 14 cm Make sure that you use the radius of the circle.
6) Find the area of this circle. 22 cm
11 x 11 x 3.14 = cm 2 22 cm
Area = Radius x Radius x Its as easy as pi.
Find the circumference of the following circles: (Write the formula that you will use.)
Formulas for Geometry Mr. Ryan Visit for more free powerpointswww.worldofteaching.com.
For Learning to Happen: Pay close attention to this lesson. Listen to my instructions to discover the area of a circle.
Area and Perimeter Yes you do need to write this..
Problem 7.4 Remember: A radius square is a square whose sides are the same length as the radius of the circle.
Area Of Shapes. 8cm 2cm 5cm 3cm A1 A2 16m 12m 10m 12cm 7cm A1A2.
5 th Grade Miss Camerons Class. The circumference of a circle is The distance around a circle Hint: Circumference remember circle around. Circumference.
Working with Shapes in Two Dimensions Two-Dimensional Objects.
Multiplying Polynomials. How do we find the area of a square?
The National Certificate in Adult Numeracy Level 2 Skills for Life Support Strategies Module 7: Perimeter, area and volume.
Objective : Calculate the area of regular quadrilaterals. o Area is the space inside a 2D shape. o A quadrilateral is a 4 sided shape such as a square.
GEOMETRY Geometry is all about shapes and their properties.
6.G.1 Perimeter and Area of Rectangles, Squares and Triangles.
Area Probability Math 374. Game Plan Simple Areas Simple Areas Herons Formula Herons Formula Circles Circles Hitting the Shaded Hitting the Shaded Without.
The shapes below are examples of regular polygons. Look at the sides and angles of each shape. Octagon rectanglehexagon triangle The following shapes.
The distance around the outside of a shape is called the perimeter. 8 cm 6 cm 8 cm 6 cm The perimeter of the shape is = 28cm. First we need.
Surface area is how much area is on the outside of a solid. We measure surface area with square units.
Of. and a to the in is you that it at be.
Geometry Formulas: Surface Area & Volume. A formula is just a set of instructions. It tells you exactly what to do! All you have to do is look at the.
Copyright©amberpasillas2010. Today we are going to find the Area of Parallelograms a nd the Area of Triangles.
Geometry Part 1B Perimeter By Julia Arnold, Dick Gill and Marcia Tharp for Elementary Algebra Math 03 online.
UNIT 8:FORMULA By: Grace Silverstein, and Samantha Stoeber!
Area Under A Curve And Writing a Riemanns Sum Catherine Bernal Period 2.
The. of and a to in is you that it he for.
The. of and a to in is you that it he was.
Circles Shape and Space. The value of π For any circle the circumference is always just over three times bigger than the radius. The exact number is called.
First of all – lets look at the windows you are going to use. At the top you have a toolbar, with all your various tools you can use when customising your.
It looks like this,… Not like this,…
Volumes Of Solids. 14cm 5 cm 7cm 4cm 6cm 10cm 3cm 4cm 8m 5m.
High Frequency Words List A Group 1. the of and.
© 2016 SlidePlayer.com Inc. All rights reserved.