Cylinder Total Surface Area?

Question

The cylinder has a height of 10 cm and a diameter of 7 cm. I know the formula to find the answer. The problem is how the multiple chose answers read. They are:

24.5 pi cm^2
94.5 pi cm^2
70 pi cm^2
122.5 pi cm^2

How exactly would I find the answer?

Answer 1

For a cylinder with height h and radius r the surface area is:

S = 2πr² + 2πrh

h = 10 cm
r = (1/2)*7 cm = 7/2 cm

So

S = 2π(7/2)² + 2π(7/2)(10) = (49/2)π + 70π
S = 24.5π + 70π = 94.5π cm²

Just leave π as π.

Answer 2

Circumfrence: pi* diameter = 7 pi
x height: 7 pi * 10 = 70 pi
+ 2 times surface area of ends= 70 pi + 2 * pi (7/2) ^2
=> 70 pi + 2 pi 49/4 => 70 pi + pi (49/2) => 70 pi + 24.5 pi

Use distribution: (70 + 24.5) pi

So 94.5. Glad I could help with your homework.

Answer 3

by using fact it somewhat is closed on the ends (they have advised you what style they have), you like the full floor area. the exterior area of the ends (which mutually style a sphere) is 4*pi*(3/2)^2 and the exterior area of the cylinder is 3*pi*12. the full area is 4*9/4*pi+36*pi = 40 5*pi m^2

Answer 4

pi = 22/7 = 3.14
When you do the calculation, just don't multiply the "pi". Just leave it like that.
Example:
find the area of the circle on the top of the cylinder:
A = pi*r^2 --> (pi times squared radius)
A = pi*(3.5)^2
A = pi*12.25
A = 12.25 pi

Good luck and have fun!

Answer 5

The correct answer here is 94.5*pi cm^2

Below are the calculations

Area of cyclinder:
2*pi*r*h = 2*pi*3.5 cm*10 cm = 70*pi cm^2

Area of ends (2*area of circle):
2*pi*r^2 = 2*pi*(3.5 cm)^2 = 24.5*pi cm^2

Surface area of cyclinder:
70*pi cm^2 + 24.5*pi cm^2 = 94.5*pi cm^2

Answer 6

Evaluate your formula without multiplying by the numerical value of pi.