Question

A cone has a height of 24 inches , a slant height of 25 inches , and a diameter of 14 inches. What is the surface area of the cone ?

A. 1,176 pi^2
B. 392 pi^2
C. 224 pi^2
D. 178 pi^2

I know how to plug in the numbers and everything but I forgot the formula to find my answer .. Can someone help me ?

Answer 1

The surface area of a cone is

\[\Large SA = \pi*r^2 + \pi*r*s\]

SA = surface area
r = radius
s = slant height

Answer 2

In this problem, r = 7 since the diameter is 14 and you cut the diameter in half to get the radius. Also, s = 25 is the slant height.

Answer 3

Thanks so much

Answer 4

So it would be ..
A = 3.14 x 7^2 + 3.14 x 7 x 25

Answer 5

I got the answer 703.36 but that's not one of the choices in the question .. Can u help me ? @jim_thompson5910

Answer 6

leave pi as it is

Answer 7

think of pi as a variable if you have to

Answer 8

Okay I'll try that

Answer 9

tell me what you get

Answer 10

I think I need help cause I'm getting a bigger number

Answer 11

what is 7^2 equal to?

Answer 12

49

Answer 13

how about 7*25, what is that equal to?

Answer 14

175

Answer 15

So...

\[\Large SA = \pi*r^2 + \pi*r*s\]
\[\Large SA = \pi*7^2 + \pi*7*25\]
\[\Large SA = \pi*49 + \pi*175\]
\[\Large SA = 49\pi + 175\pi\]
\[\Large SA = 224\pi\]

Answer 16

notice how I added 49pi to 175pi to get 224pi

similar to me saying 49x+175x = 224x

Answer 17

Ohhh I know where I missed up
Thanks so much

Answer 18

glad to be of help