Study Guide Unit 2

Study Guide Unit 3: Circles

Multiple Choice

What does PERIMETER mean?

• Amount of space inside the object

• Distance around the object

Perimeter: Around the Object

What do we know?

Multiple Choice

What shapes make up the object?

• 2 Triangles and 1 Square

• 3 Squares and 2 Circles

• 3 Squares and 1 Circle

Notice what parts of the shapes touch the PERIMETER

One Circle and the 4 outside edge of the squares

Multiple Choice

What is the PERIMETER of JUST the square outside edges?

• 10

• 20

• 30

• 40

Multiple Select

Which formulas could we use to find the PERIMETER of the circle?

•  $A=\pi r^2$  

•  $C=2\pi r$  

•  $C=\pi d$  

Using the correct Formula is KEY

 $C=\pi d\ \ \ or\ \ \ C=2\pi r$  

Multiple Choice

 $C=2\pi r\ \ or\ \ C=\pi d$  

What is the PERIMETER of the circle IN TERMS OF PI?

•  $10\pi$  

•  $20\pi$  

• 31.4

• 62.8

Putting it all together

• Squares: 40

• Circle:

   $20\pi$  

• ANSWER:   $20\pi\ +\ 40$  

Poll

How are you feeling about working with circumference of circles!?!

• Got it down

• Feel pretty good

• still working on it

• oh my.....

Poll

How are you feeling about reading graphs to determine if they are proportional (origin and straight line)?

• This is easy

• Once I see the graph I got it

• Still looking to understand

• help me

Multiple Choice

The Perimeter of the square is:

• 5

• 10

• 30

• 40

Multiple Choice

To find the PERIMETER of the circle we need 1/4 of the circumference. The answer is.....

• 7.85

• 15.7

• 3.14

• 5

Putting it all together

• Perimeter of the Square: 30

• Circumference of 1/4 circle: 7.85

• Answer: 82.85

Now for the Area

 $A=l\cdot w\ \ \ \ \ \ \ A=2\pi r^2$  

Multiple Choice

 $A=l\cdot w$  

Using the formula for the Area of a square, which equation below helps us solve for the area of the square in the picture

• (10 x 10)

• (5 x 10)

• (10 x 10) $\times\frac{3}{4}$  

• (10 x 10)  $\times\frac{1}{4}$  

Multiple Choice

Area of the Square is......

• 100

• 50

• 75

Multiple Choice

The area of the quarter circle is......

 $A=\pi5^2\ \cdot\ \frac{1}{4}$  

• 78.5

• 19.6

• 31.4

Putting it all together

Area of the Square: 75

Area of the 1/4 Circle: 19.6

Total Area: 94.6

The next slides will need your attention

Multiple Choice

A circle with a radius of 50 has an area closest to what?

• 157

• 314

• 7854

• 15708