Question

Geometry help please

Answer 1

Do you know the formulas for the surface area and lateral surface area of a cone?

Answer 2

SA = πr2 + πrl

Answer 3

So in your problem, r = 12 and l = 21. Substitute and solve.

Answer 4

Sa=3.14*12*2 + 3.14*12*21

Answer 5

866.64

Answer 6

what did i do wrong? @Mertsj

Answer 7

I'm not sure. What do you get for 3.14 x 12^2

Answer 8

452.16

Answer 9

Do you know that the formula is:
\[SA=\pi r^2+\pi rl\]

Answer 10

And what about pi x12x21?

Answer 11

791.28

Answer 12

Add those two numbers together.

Answer 13

1243.44

Answer 14

So if you carried more digits in pi you would get 1244.1 so now we have narrowed it down to 2 or 4.

Answer 15

Now hunt up your formula for lateral surface area of a cone and plug into that.

Answer 16

1/2pl+B

Answer 17

Where did you get that?

Answer 18

Google "lateral surface area of a cone"

Answer 19

i did and that came up

Answer 20

Lateral surface area of a cone = π × r × l,

Answer 21

Plug into that

Answer 22

You've already done it once, haven't you? It the first part of the formula for the total surface area.

Answer 23

3.14*12*21 = 791.28

Answer 24

So what is your answer?

Answer 25

D

Answer 26

Good job!!

Answer 27

thank you for the help

Answer 28

yw