Question

Find the surface area of the figure below.

A. 203.1 ft2
B. 301.59 ft2
C. 318.74 ft2
D. 395.84 ft2

i am so confused on this .. i am trying to use the c^2=b^2 and a^2 different ways but its just not working out . what am i doing wrong ?

Answer 1

@gaara438125

Answer 2

we need to find the height first, which i believe we already found was 16.16 correct?

Answer 3

this is a completely different question than before . lol . i'm so unsure with this one .

Answer 4

ok i see what's different :P
we need to find a side (the height) we know the hypotenuse (the slant) and one side so
b^2 = c^2 - a^2
c = 15
a = 6

Answer 5

my answer was 189 . what do i do from there ? because that answer isn't available in the answer choices .

Answer 6

@gaara438125
@JakeV8
@Grim0519

Answer 7

You were close... just not done with the last step on finding that length:

b^2 = c^2 - a^2
c = 15 a = 6
b^2 = 225 - 36
b^2 = 189

But you want "b", not "b squared"... you forgot to take the square root of 189.

Answer 8

do you know the surface area of cone=?

Answer 9

But then, yeah, you need surface area, not just the length of the outside edge.

I don't have that formula handy...

Answer 10

you are right @JakeV8

Answer 11

the square root of 189 is : 13.7477270849

Answer 12

I'm not sure you needed to find that after all... but good practice with the pythagorean theorem :)

The formula for surface area of a cone needs the diagonal length, not the height.

The formula I found online (yay Internet!) was:

pi * r^2 + pi * r * s

where "r" is the radius (shown as 6) and "s" is the diagonal length of the cone's edge, (shown as 15).

Answer 13

http://0.tqn.com/d/math/1/0/t/L/conerr.jpg

Answer 14

woot woot ! got my answer (:

395.84 ft^2 (: (: (:

Answer 15

Good work... you just needed to use the formula.

Answer 16

thank you so much for helping me out (:

Answer 17

Glad to help :)