How to find the surface area of a cylinder with a diameter of 6ft and a height of 20cm using 3.14 rounded to the nearest whole number. (I cant figure it out my book doesn't give an example of it just a radius formula and ive tried searching the formula but i cant find any websites that show me how to do it or whats the formula) please help.

Answer 1

Area of a circle = d ^ 2 * pi / 4

Circumference of a circle = d * pi

Area of a rectangle = Circumference * height = d * pi * h

Area of a cylinder = 2 * Area of a circle + Area of a rectangle

A = 2 * d ^ 2 * pi / 4 + d * pi * h

So :

A = 2 * d ^ 2 * pi / 4 + d * pi * h =

d ^ 2 * pi / 2 + d * pi * h =

d * pi * ( d / 2 + h )

A = d * pi * ( d / 2 + h )

______________________________
Remark:

r = d / 2

A = d * pi * ( d / 2 + h ) is equivalent of:

A = 2 * r * pi * ( r + h )
____________________________

pi rounded to the nearest whole number = 3

1 in = 2.54 cm

1 ft = 12 in = 12 * 3.54 = 30.48 cm

6 ft = 6 * 30.48 = 182.88 cm

Now you can calculate the surface area of a cylinder

Answer 2

Surface Area
A = 2•pi•r^2 + 2•pi•r•h

The radius is half the diameter

2(3.14)3^2 + 2(3.14)3•20
56.52 + 376.8 = 433.32

A = 433cm

Answer 3

Explanation

r = d / 2

d = 2 r

For that reason

A = d * pi * ( d / 2 + h ) =

2 * r * pi * ( r + h )

Answer 4

thank you guys I figured it out! and especially to Chelle (:.

Answer 5

omg just give the answer u retuards