Area of a cylinder?

Question

The Height is 9cm and the diameter of the circle is 9cm i think the circumference is 28.3 (1dp)
Also please could you state how you did it
Thanks

Answer 1

Area of the cylinder = pi.d.h + 2.pi.d^2/4

Circumference = pi.d = 3.1416 x 9 = 28.27..cm

Area = 3.1416 x 9 x 9 + 2 x 3.1416 x 9 x 9 / 4

= 254.4696 + 127.2348 = 381.7044 sq.cm

Answer 2

H = 9 cm
D = 9 cm

Area of cylinder ("side" only, not ends) = Circumference x H
( We have a cylinder, not a can.)

Circumference = pi * diameter

Area = 9cm * pi * 9 cm = 81 pi square centimeters.

Answer 3

the areas of a cylinder is the sum of both the circles plus the rectangle that form the "wall" of the cylinder. it has been more than a decade since i last did this in school, so i cant remember the right terms.

anyway, it should be
2x (pi r square) + circumference x height
= (2 x 3.14 x 4.5 x 4.5) + (28.3 x 9)
use your calculator!

Answer 4

Is it an open or closed cylinder?
If it's an open cylinder:
Area of base = πr^2
= (22/7)(9/2)^2
= 63.64 cm^2

Area of curved wall = 2πrh
= circumference x h
= 28.3 x 9
= 254.57 cm^2

Total area of open cylinder = 63.64 + 254.57
= 318.21 cm^2



If it's a closed cylinder:
Area of base and cap = 2 x πr^2
= 2 x (22/7)(9/2)^2
= 127.29 cm^2

Area of curved wall = 318.21 cm^2

Total area of closed cylinder = 127.29 + 318.21
= 445.50 cm^2



P.S. The only difference in the area of both cylinders is that the area of the closed cylinder includes an extra πr^2 (ie. area of cap) whereas the open cylinder does not.

Answer 5

area = π D H = π (9 ) (9) = 254.47 cm.²