## mckenzieandjesus one year ago What is the surface area of the cone? 175π cm2 224π cm2 147π cm2 273π cm2

1. mckenzieandjesus

2. mckenzieandjesus

im using this site http://www.web-formulas.com/Math_Formulas/Geometry_Surface_of_Cone.aspx but got the wrong answer and kind of confused how to put it all in the formula..

3. NathalyN

A=πr(r+h2+r2)

4. jdoe0001

$$\large \textit{volume of a cone}=\cfrac{\pi r^2 h}{3}\qquad \begin{cases} r=radius\\ h=height \end{cases}$$

5. jdoe0001

hmm shoot .. surface area... ok

6. mckenzieandjesus

13891 9/25?

7. mckenzieandjesus

@NathalyN

8. jdoe0001

$$\bf \textit{total surface area of a cone}=\pi r\sqrt{r^2+h^2}+\pi r^2\qquad \begin{cases} r=radius\\ h=height \end{cases}$$

9. mckenzieandjesus

16909.214?

10. mckenzieandjesus

or 703.36 those are the answers im getting..

11. jdoe0001

hmm so.. which one did you get?

12. jdoe0001
13. mckenzieandjesus

so $3.14*7\sqrt{7^{2}}+24^{2} + 3.14*7^2 =$ 16909.214

14. mckenzieandjesus

yeah and i got that answer u got by doing it another way.. but none of those are on my answer choices..

15. mckenzieandjesus

@jim_thompson5910

16. jdoe0001

ohh hmmm your choices are in $$\huge \pi$$ terms thus... you need to keep the $$\huge \pi$$ without multiplying it

17. mckenzieandjesus

so how do i do that?

18. jdoe0001

well.. just don't multiply the $$\pi$$ and keep it as is, as a variable per se

19. mckenzieandjesus

$7*\sqrt{7^2+24^2} + 3.14*7^2$

20. mckenzieandjesus

or wait..

21. jdoe0001

one sec

22. mckenzieandjesus

$7*\sqrt{7^2+24^2} * 7^2 = 8575$

23. mckenzieandjesus

okay.. still lost

24. jdoe0001

hmmm have a typo there one sec $$\bf \textit{total surface area of a cone}=\pi r\sqrt{r^2+h^2}+\pi r^2\qquad \begin{cases} r=radius\\ h=height \end{cases} \\ \quad \\ \pi r\sqrt{r^2+h^2}+\pi r^2\implies \pi r(\sqrt{r^2+h^2}+r)\impliedby \textit{common factor} \\ \quad \\ \begin{cases} r=7\\ h=24 \end{cases}\implies \pi \cdot 7(\sqrt{7^2+24^2}+7)\implies \square ?\pi$$

25. mckenzieandjesus

224?

26. jdoe0001

yeap

27. mckenzieandjesus

thank you

28. jdoe0001

so in $$\pi$$ terms is $$\large 224\pi$$

29. mckenzieandjesus

Can u finish helping me on my other question please?