Find the surface area of the regular pentagonal pyramid. The apothem of the pentagon is 5.5cm and AB =10 cm. The edge base length at the bottom of the figure is 8cm. Round answers to the nearest tenth of a unit.

- anonymous

- schrodinger

I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!

At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga.
Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus.
Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.

Get this expert

answer on brainly

SEE EXPERT ANSWER

Get your **free** account and access **expert** answers to this

and **thousands** of other questions

- anonymous

Surface area = 200 cm^2
can anyone see if this is right?

- amistre64

apothem is the face height and not the pyramid height right?

- amistre64

what is AB mean?

Looking for something else?

Not the answer you are looking for? Search for more explanations.

## More answers

- amistre64

prolly height of pyrimaid

- anonymous

apothem is a line segment from the center of the polygon perpendicular to one of its sides....
AB is ... A is the tip of the pyramid... to the base.. an edge of a side

- anonymous

B is on the bottom

- anonymous

pentagonal 5 sides

- amistre64

##### 1 Attachment

- anonymous

looks good

- amistre64

8*5.5*5 is side areas, do we include the bottom as well?

- anonymous

l^2 = (5.5)^2 + (4)^2
l = sqrt 5.5^2 + 4^2
sqrt
yea... I think I did

- anonymous

sqrt 30.25 + 16
sqrt 46.25
p = 6.8
1/2(40)(6.8) + 8^2
= 200

- amistre64

sqrt((4^2) + (5.5^2)) = 6.80073525 doesnt = 10
sqrt((8^2) + (5.5^2)) = 9.7.... is close to 10
If the edge AB that runs slong the side is 10, that means the base is 16

- amistre64

##### 1 Attachment

- anonymous

yes

- amistre64

8 * 5 * 5.5 = 220 for sides areas .... but to include the base we'd have to do some more calculations

- anonymous

ok well its just asking for the surface area.... LA + B

- amistre64

this is what I got so far;
I can calculate the missing parts the hard way... but thats just how I role lol

##### 1 Attachment

- anonymous

ha oh boy

- amistre64

16^2 = 2s^2 -2s^2 cos(74)
16^2 = s^2(2-2cos(74))
16^2
-------- = s^2
2-2cos(74)
Area in red = (s^2 sin(74))/2

- anonymous

oh wow... so um... tell me you get 200 LOL

- amistre64

:) I get about 85 there ... if I did it right but *5
gotta chk it again make sure I aint messed it up

- amistre64

hah!! i had 72 but used 74 lol .....

- anonymous

ok I'll check again too... good eye

- amistre64

I get abt 440.5 for the bottom area that way

- anonymous

i wonder if there is a calculator to find the area... let me investigate LOL

- amistre64

i think I see an easier way; tan(54) = h/8
h = 8 tan(54)

##### 1 Attachment

- amistre64

16/2 = 8
8 * 8tan(54) = area of red tri
5* area red tri = area base

- amistre64

= 215.6

- amistre64

220
215.6
-------
435.6 abt for the surface areas

- anonymous

hey whats the side length, and what is the slant length

- anonymous

is 10 slant and 8 side

- amistre64

the side length of the pyramid is 10; and the slant is 5.5

- amistre64

that 215.6 is off

- anonymous

I thought the apothem was 5.5

- amistre64

aint that the slant?

- amistre64

http://www.wolframalpha.com/input/?i=area+pentagon+side+%3D16
I keep coming to 440.442 as area of base

- anonymous

the calculator is asking for
apothem length
side length
slant length
enter height

- anonymous

http://easycalculation.com/area/pyramid.php
pentagonal pyramid

- amistre64

5.5 16 10 is what I used

- amistre64

Sa = 620 ....
220
440.5
------ so we are close
660.5

- amistre64

edge base length is what I cant be to sure about; how do you describe that?

- anonymous

ha your awesome.... hey it says round to the nearest tenth unit...

- anonymous

the edge where the number is in my book LOL on AB?

- anonymous

thats my lingo... lol

- anonymous

I was trying to describe whatever you were asking

- amistre64

:) does my interpretation for this look good then?

##### 1 Attachment

- amistre64

if I got the 8 in the right place... then im good to go

- anonymous

the 8s are at the bottom of base of the pyramid

- amistre64

yes; the red is just a reflection into the base under the pyramid

- anonymous

where alll the edges meet and creat the pentagonal base

- amistre64

yes

- anonymous

A is the top of the pyramid.... and B is at the bottom with the 8s

- anonymous

AB is a side of one of them triangles

- amistre64

the tiny dancer is what I have pictured

##### 1 Attachment

- anonymous

well there it is!!! yep looks just like it LOL

- amistre64

then:
Sa = 5(face area) + 5(redbase area)
Sa = 5(5.5*16/2) + 5(8*8tan(54)/2)
Sa = 660.442

- amistre64

16*8tan(54)/2 lol

- anonymous

oh wow...

- amistre64

we got a way to verify this?

- anonymous

yea that calulator if I know the right numbers

- anonymous

I dunno... I'm going with what you did!

- amistre64

ive been trying to define apothem, slant heaight, and all that stuff; but nothing is consistant.
apothem of a pyramid most likely means the height of a face;
slant height also means distance up the face; so I cant seem to determine what any of it really means..

- anonymous

85.8253
slnat height is 10? and sides are 5

- amistre64

do you know how to do a screenshot?

- anonymous

no

- amistre64

do you see the "PrtScrn" key that you never use up there with the "pause", and "scroll lock" keys?
press it

- anonymous

k

- amistre64

now open up your 'paint' program and hit your 'ctrl + v' keys to paste it. and let me know if it worked

- anonymous

yes

- amistre64

save it to your desktop as a jpeg and attach it to this post

- anonymous

##### 1 Attachment

- anonymous

is that what you wanted?

- amistre64

yep; now do that to the screen that has the problem on it :)

- anonymous

the problem is is in my book

- amistre64

can you take a picture of it? and put it on the computer? maybe a scanner?

- anonymous

ok hang on

- anonymous

ok

##### 1 Attachment

- anonymous

is that what you wanted LOL

- amistre64

yes :)

- anonymous

kk

- amistre64

the apothem of the pentagon is 5.5 ; thats the length from the center of the base out to the base edge... much better

- anonymous

just an FYI regular pyramid formula is LA + B
Yes , i thought I told you that :)

- amistre64

this is the correct picture I needed lol

##### 1 Attachment

- anonymous

I still get 200

- amistre64

Sa = 5(8*sqrt(10^2+4^2)/2) + 5(8*5.5/2)
Sa = 5(4*sqrt(116)) + 5(4*5.5)
Sa = 20sqrt(116) + 20(5.5)
Sa = 325.406592 ....

- anonymous

what did we determine the slant length is

- amistre64

the slant length is the missing leg of the right tri formed by half the base and a hyp of 10
sh^2 + 4^2 = 10^2
sh = sqrt(100 - 16) .. doh!! I added

- anonymous

9.16

- amistre64

http://www.wolframalpha.com/input/?i=5%284*sqrt%2810^2-4^2%29%29%2B5%284*5.5%29

- anonymous

9.17

- amistre64

Sa = 293.303

- anonymous

how guaranteed.... I get 366.6

##### 1 Attachment

- amistre64

is side 10 or 8?

- amistre64

height should be abt 7.331

- anonymous

side is the top of pyramid AB 10 no??? whats 8? base I dunno

- anonymous

who ever invented math is wasting valuable life time for me!!! :(

- amistre64

... the base of this thing is abt 110.1111

- anonymous

thats the perimeter of the base... 5(8) = 40 I thought

- amistre64

183.303 is the lateral area
110.111
--------
293.414

- amistre64

##### 1 Attachment

- anonymous

Ok I give up on this one... I am taking your word!

- amistre64

and this for the base lol

##### 1 Attachment

- anonymous

you have some neat sites

- anonymous

when I think I understand .... I DONT!!!

- amistre64

:) thnx take a break, and get aome air

- amistre64

I gotta drive up to the veranda and setup for my laptop; librarys closing...

- anonymous

ok ... I need to review... take my notes... and on to the next.. LOL
Thank you

- anonymous

I'll be here!!

Looking for something else?

Not the answer you are looking for? Search for more explanations.