-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:

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

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

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 = ■

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