Find the Surface Area of a cone with a diameter of 10 cm and a height of 12 cm.
Use pi = 3.14.

Question

Find the Surface Area of a cone with a diameter of 10 cm and a height of 12 cm. 
Use pi = 3.14.

anonymous · Answer

$$SA=\pi*rs+\pi*r^2$$
The radius would be 5 cm and so the slant height would be 13 cm
Thus the SA=90*pi or 282.74

anonymous · Answer

Total surface area of the cone:
$$SA=\pi*r ^{2}+\pi*r*\sqrt({r}^{2}+h ^{2})$$
plug-in your numbers :)

amistre64 · Answer

i get:

$$Sa=pi\ r\sqrt{r^2+h^2}$$

amistre64 · Answer

but thats not accounting for the area of the base is it...

anonymous · Answer

ok so 3.14*5 * square root of 25+144?

amistre64 · Answer

yeah; which is 65pi ; but methinks thats just the lateral area; if we include the base add another 25pi?

anonymous · Answer

15.7*13 so the final answer is 204.1?

anonymous · Answer

if im using 3.14 as pi

amistre64 · Answer

90*3.14 = 282.6 ?

anonymous · Answer

wait where did u get 90?

amistre64 · Answer

i tend to confuse lateral area and surface area; cause im old :)

amistre64 · Answer

65 pi is the lateral area; i think surface area adds the base area which is another 25 pi

anonymous · Answer

To get the lateral area you multiply the slant area by the radius by pi.
However, you also have to add the base area which is pi* radius squared.

anonymous · Answer

So amistre is right, it is 65pi+25pi=90pi

anonymous · Answer

so did i do that right with the formula that was given above?

anonymous · Answer

im looking for surface area though

anonymous · Answer

Yes the surface area is the lateral area + the base area which is 90 pi

amistre64 · Answer

65*3.14 is 204.1; but thats not the whole surface area ....

anonymous · Answer

then what is?

amistre64 · Answer

add another 25 pi to it to include the area of the base

90pi altogether

amistre64 · Answer

282.6

amistre64 · Answer

pi r^2 = area of the base

pi 5^2 = 25pi

anonymous · Answer

i am very confused lol can u show me the steps?

amistre64 · Answer

attachment

amistre64 · Answer

Add the Area of the sides and the Area of the Base to get total surface area

amistre64 · Answer

$$Sa=(3.14(r)*\sqrt{r^2+h^2})\ +\ (\pi \ r^2)$$

anonymous · Answer

so 3.14*25 + 3.14*10 * sqrt 25+144?

amistre64 · Answer

yes

anonymous · Answer

3171.4*13=41228.2 ?

amistre64 · Answer

you hit a wrong key i think :)

3.14(5^2) + 3.14(5)(13)

amistre64 · Answer

282.6 is what you should get

anonymous · Answer

oh i got it now lol my bad

amistre64 · Answer

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