Text Book Questions

Question 9:

Kaitlyn and Hakim each bought a tube of candy. Both containers cost the same amount. Which container required more plastic to make?

Candy tube A:

d/2 = r

7/2 = r

3.5 cm = r

TSA= (2 x Pi x r x r)+(2 x r x Pi x h)

TSA= (2 x 3.14 x 3.5 x 3.5)+(2 x 3.5 x 3.14 x 122)

TSA= (76.93cm2)+(2681.56cm2)

TSA= 2758cm2

The amount of plastic needed to make tube A is 2758cm2.

Candy tube B:

d/2 = r

11/2 = r

5.5 cm = r

TSA= (2 x Pi x r x r)+(2 x r x Pi x h)

TSA= (2 x 3.14 x 5.5 x 5.5)+(2 x 5.5 x 3.14 x 85)

TSA= (189.97cm2)+(2935.9cm2)

TSA= 3125.87cm2

The amount of plastic needed to make tube B is 3125.87cm2.

The tube of candy that needs more plastic is B.

Question 10:

Paper towel is rolled around a cardboard tube. Calcula

te the outside surface area of the tube.

d =2r

d =2 x 2

d =4cm

c = Pi x d

c = 3.14 x 4

c = 12.56cm

l x w = area of a square

12.56 x 27.5 = area of a square

345.4cm2 = area of a square

The out side surface area of the tube is 345.4cm2.

Cylinder Volume and Volume ProblemsQuestion 1:

Answer:

Jumbo Popcorn

d/2=r

20/2=r

10cm=r

v=(pir^2)h

v=(3.14x10x10)40

v=314cm^2x40cm

v=12650cm^3

Popcorn lover's

d/2=r

30/2=r

15cm=r

v=(pir^2)h

v=(3.14x15x15)20

v=706.5cm^2x20cm

v=14130cm^3

Here is my math video

If Martha wants to get more popcorn for her money she should by the popcorn lover's container.

Question 2:

d/2=r

10/2=r

5cm=r

v=(pir^2)h

v=(3.14x5x5)40

v=78.5cm^2x40cm

v=3140cm^3

d/2=r

8/2=r

4cm=r

v=(pir^2)h

v=(3.14x4x4)40

v=50.24cm^2x40cm

v=2009.6cm^3

3140cm^3 - 2009.6cm^3=1130.4cm^3

Meldrick's Circle Surface Area Post

Here are the notes that we took down in class:

-the bases of a cylinder are circles

-the radius is half a diameter

-the diameter cuts a circle in half

-the circumference is the perimeter of a circle

-pi - the ratio between the circumference and diameter- 3.14159.. and on.. and on- you get it, right?

Here are the formulas that we also took down in class:

Radius

d/2=r

Diameter

2r=d or c/pi=d

Circumference

pi(d)=c *remember, brackets mean multiplying*

Area (of a circle)

Pi(r squared)

For example:

Here are the homework circles:

This is a link that is dedicated to circles.

Here is a link to a video that I couldn't embed.

7.3


a) When the radius of a cylinder is doubled, the volume of a cylinder is multiplied by 4.
EX.
v = π*r^2*h
v = 3.14*1²*1
v = 3.14*1*1
v = 3.14 cm³

v = π*r^2*h
v = 3.14*2²*1
v = 3.14*4*1
v = 12.56 cm³

b)When the height of a cylinder is doubled, the volume of the cylinder is doubled.
EX.
v = π*r^2*h
v = 3.14*1²*1
v = 3.14*1*1
v = 3.14 cm³

v = π*r^2*h
v = 3.14*1²*2
v = 3.14*1*2
v = 6.28 cm³

7.4

The volume of the triangular prism shown is 48 cm^3. What is the value of the missing measurement?
The value of the missing measurement is 5.
EX.

[v/h²]*2 = area of the base

[48 cm³/8 cm]*2 = area of the base

6 cm²*2 = area of the base

12 cm² = area of the base

area of the base/h¹ = base

12 cm²/4 cm = base

3 cm = base

Now, if...

h¹ = a

base = b

■ = c

a²+b² = c²

4²+3² = c²

16+9 = c²

25 cm² = c²

sqrt of c² = c

sqrt of 25 = c

5 = c

5 = ■