Question

Sally plans to cover this model of a half moon completely with silver foil. How many square centimeters of silver foil would Sally need to cover the model completely?

Answer 1

the formula for a sphere is 4 pie r squared

Answer 2

I mean

Answer 3

the surface area

Answer 4

however, does it make a difference since it is a half circle instead of a full circle?

Answer 5

the answer I got for the whole surface area was 1,017

Answer 6

approximately

Answer 7

however, the answer is suppose to be approximately 763.7

Answer 8

yes, surface area of a hemisphere is half that of sphere.
Wait, i am finding answer.

Answer 9

is the formula for a hemisphere 1/2(4 pie r squared)

Answer 10

It seems to be incorrect since my answer came out to be approximately 508.9

Answer 11

We need the Curved Surface Area of Hemisphere as the top face not needed
\[CSA=2\pi r^{2}\]
= 2* 22/7*(9)^2
=44/7*81
= 509.1 cm^2

Answer 12

so that was close to 508.9

Answer 13

but that answer doesn't come out to be right :(

Answer 14

ya i got it.
We need to include top face.Hence,we need to find out the TSA of Hemisphere.

Answer 15

but there is only a hemisphere

Answer 16

shouldn't the area of a hemisphere be half the area of a whole sphere?

Answer 17

TSA=3pi r^2
= 3*22/7*(9)^2
=66*81/7
= 763.7 cm^2

Answer 18

can I ask you something?

Answer 19

yes

Answer 20

why don't they include these formulas in the lessons?

Answer 21

lol

Answer 22

which book are you studying?

Answer 23

online course

Answer 24

It did not see the TSA formula stated in the review

Answer 25

I did not see the formula in the review

Answer 26

only 4 pie r squared

Answer 27

lol

Answer 28

well!
In case of Sphere and Hemi. you can yourselve find the formula.

Answer 29

yeah...

Answer 30

but still...

Answer 31

they need to include every formula in the review that will be covered on the test...

Answer 32

lol

Answer 33

so the formula for the TSA of a hemisphere is 3 pie r squared

Answer 34

ty