Question

MEDAL & FAN ANYBODY ?
Find the surface area of the cone in terms of pi.
A. 54pi cm.2
B. 99pi cm.2
C. 51pi cm.2
D. 49.5pi cm.2

Answer 1

172.45

Answer 2

172.45 :)

Answer 3

@awesomeness812 thats not an answer choice...

Answer 4

you either times or add 15 and 3

Answer 5

well howd you get 172.45 @awesomeness812 ?

Answer 6

\(SA = \pi r s + \pi r^2\)

Plug in what we know:

\(SA = (3.14)(3)(15) + (3.14)(3)^2\)

Simplify exponent:

\(SA = (3.14)(3)(15) + (3.14)(9)\)

Multiply the 3 numbers:

\(SA = 141.3 + (3.14)(9)\)

Multiply the 2 numbers:

\(SA = 141.3 + 28.26\)

Add:

\(SA = 169.56\)

Answer 7

google

Answer 8

calaorot

Answer 9

@iGreen so whats the answer with pi ?

Answer 10

I have no idea what it means by 'in terms of pi'..let me do a quick search.

Answer 11

@iGreen thanks . i appreciate it

Answer 12

google

Answer 13

I think you need the height of the cone..but it doesn't give that..just the length and the radius.

Answer 14

Okay, first we find the area of the base(circle at the bottom):

Area of a circle = \(\pi r^2\)

\(\pi(3)^2\)

\(\pi(9)\)

So we have \(9\pi\).

Answer 15

Now we have to find the lateral area, but we need to find the height first.

\(h = \sqrt{l^2 - r^2}\)

Plug in the terms:

\(h = \sqrt{15^2 - 3^2}\)

Simplify exponents:

\(h = \sqrt{225 - 9}\)

Subtract:

\(h = \sqrt{216}\)

\(h = 14.7\)

Answer 16

so now you would do 15 , the same process ?

Answer 17

Now we can plug the height and the radius in the Pythagorean Theorem:

\(a^2 + b^2 = c^2\)

\(14.7^2 + 3^2 = c^2\)

\(216.09 + 9 = c^2\)

\(225.09 += c^2\)

\(c \approx 15\)

Now we can find the lateral area(circumference of base)

\(C = 2\pi r\)

\(C = 2\pi 3\)

\(C = 6\pi\)

Now add this to the 15 we got from the Pythagorean Theorem:

\(6\pi \cdot 15\) = \(90\pi\)

Now add this to the area of the circle we found:

\(90\pi + 9\pi = 99\pi\)

Answer 18

So \(99 \pi\) is your final answer..

Answer 19

@ninaesb

Answer 20

@iGreen thanks

Answer 21

No problem.

Answer 22

@iGreen that was actually wrong...