Question

A right cone has a base diameter that is 6 cm and a slant height that is 27 cm. What is the surface area of the cone?

81π cm2

84π cm2

162π cm2

90π cm2


Please explain.

Answer 1

@jim_thompson5910 @jhonyy9

Answer 2

I know how to do it, but I cannot get an answer with pi left out

Answer 3

why not get it witout pi - just dont use in your calcules this value of pi of 3,14 and what you get this number will use to answer togheter with pi

Answer 4

ok. ?

Answer 5

Oh okay... so it's 81pi^2

Answer 6

pi squared not is right
the unit measure you need writing squared - ok. ?

Answer 7

Lol the first one, then?

Answer 8

That's what I meant

Answer 9

so will be 81pi cm^2

Answer 10

Okay

Answer 11

do yu understand it now sure right ?

Answer 12

Yeah I get it. I knew how to do it, but I was confused on the pi part.

Answer 13

Can you quickly check this one: http://prntscr.com/bg2f29

Answer 14

you made a typo somewhere. The answer isn't 81pi

Answer 15

I'm referring to the first question at the top

Answer 16

Surface area of a cone
\[\Large SA = \pi*r*(r+s)\]
In this case
r = 3 is your radius
s = 27 is the slant height
\[\Large SA = \pi*r*(r+s)\]
\[\Large SA = \pi*3*(3+27)\]
\[\Large SA = \pi*3*(30)\]
\[\Large SA = 90\pi\]

Answer 17

Wait, what?

Answer 18

The equation for the surface area of the cone with slant height is A=πrl+πr^2

Answer 19

r = 3 is the radius
L = 27 is the slant height
\[\Large SA = \pi*r*L+\pi*r^2\]
\[\Large SA = \pi*3*27+\pi*3^2\]
\[\Large SA = \pi*81+\pi*9\]
\[\Large SA = 81\pi+9\pi\]
\[\Large SA = 90\pi\]

Answer 20

The formula I used is in a different form but it's equivalent to your formula

Answer 21

JIm sorry but i think Rose mean total area and you wrote surface area what mean lateral
area - than i m right ???

Answer 22

Oh... okay. @jhonyy9 I need the surface area of the cone

Answer 23

@jim_thompson5910 Is 90pi cm^2 correct?

Answer 24

`Is 90pi cm^2 correct?`
yes @rose4825

Answer 25

@jim_thompson5910 Can you check this one? http://prntscr.com/bg2f29

Answer 26

ok checking now

Answer 27

9 is correct