anonymous
  • anonymous
The area of the base of a prism is 21 cm2. The perimeter of the base is 20 cm. The height of the prism is 8 cm. What is the surface area of the prism?
Mathematics
  • Stacey Warren - Expert brainly.com
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SOLVED
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katieb
  • katieb
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
anonymous
  • anonymous
@dan815 @♪Chibiterasu
anonymous
  • anonymous
@satellite73 @SolomonZelman @Miracrown @micahm @UsukiDoll @Astrophysics
anonymous
  • anonymous
can some one help me

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More answers

micahm
  • micahm
openstudy.com/updates/54e4ad6ce4b0aba126e81022 copy and paste this in a new window
MrNood
  • MrNood
you do not know the shape of the base but you do knw the perimeter when you make the base int a prism you end up with a number of rectagular sides the height of EACH of these rectangles is 8 and the summ of ALL their widths is 20 so - what isa the area of all the side faces?
anonymous
  • anonymous
i already saw that it doesn't help
anonymous
  • anonymous
@micahm
micahm
  • micahm
https://www.google.com/search?q=The+area+of+the+base+of+a+prism+is+21+cm2.+The+perimeter+of+the+base+is+20+cm.+The+height+of+the+prism+is+8+cm.+What+is+the+surface+area+of+the+prism%3F&rlz=1C1GGGE___US571US573&oq=The+area+of+the+base+of+a+prism+is+21+cm2.+The+perimeter+of+the+base+is+20+cm.+The+height+of+the+prism+is+8+cm.+What+is+the+surface+area+of+the+prism%3F&aqs=chrome..69i57&sourceid=chrome&es_sm=122&ie=UTF-8#q=The+area+of+the+base+of+a+prism+is+21+cm+2.+The+perimeter+of+the+base+is+20+cm.+The+height+of+the+prism+is+8+cm.+What+is+the+surface+area+of+the+prism?
anonymous
  • anonymous
i know that but don't know how to get the answer
MrNood
  • MrNood
|dw:1449753823180:dw| you have a number of rectangular vertical faces the sum of their bases is 20, and ALL have a height of 8 so what is their area?
MrNood
  • MrNood
|dw:1449753945397:dw|
anonymous
  • anonymous
so
anonymous
  • anonymous
how do i get the answer
welshfella
  • welshfella
you can find the dimensions of the base by solving the system of 2 equations 2w + 2l = 20 lw = 21 wher l and w are the length and width i am assuming that the base is rectangular
MrNood
  • MrNood
so have a little think do a little work discuss your working here....
anonymous
  • anonymous
k
anonymous
  • anonymous
can u show how to do get the answer
MrNood
  • MrNood
@welshfella you cannot make that asumption and oyu do not need to all the sides bottom edges ADD to 20 all the sides height is 8 so you can work out the total area just from that info
anonymous
  • anonymous
u can't
anonymous
  • anonymous
16
anonymous
  • anonymous
@♪Chibiterasu
anonymous
  • anonymous
can u show me how to get the answer
MrNood
  • MrNood
yes you can you do not know haow many edges there are but if they were of lenght a,b,c,d .... etc then the area of 1 side would be 8a, then 8b + 8 c etc 8a+8b + 8c +...... = 8(a+b+c+......) but you know that the sum of a+b+c+..... = 20 so there is the answer to the area of the sides
anonymous
  • anonymous
@dan815 @Anaise @AloneS @Daniellelovee @Deadly_Roses @dakid88 @Diana.xL @gibbs @HELLOMYNAMEISKAM @HS_CA @hoots89 @helpppppppppp @jameskang1015 @jebonna @jakyfraze @Joehoffy @Johan14th
dakid88
  • dakid88
Allright. A prism is a 3 faced structure made of equilateral triangles
welshfella
  • welshfella
@MrNood yes you are right
MrNood
  • MrNood
I assume by tagging all those people you are expecting one of them to give oyu the answer I have given you ALL except the last step to working outth esides The prism also has 2 identical ends - and oyu know the area of 1 end is 21
dakid88
  • dakid88
let one side be x. the perimiter of the base, 3x = 20
dakid88
  • dakid88
The surface area of a prism = 2 × area of base + perimeter of base × H
MrNood
  • MrNood
@dakid88 that is not correct a Prism is ANY polygon base shape - NOT just a triangle You are thinking of a pyramid My answer above works for ALL prisms
anonymous
  • anonymous
u are not showing me how to get to the last step
dakid88
  • dakid88
yes the answer is 2
gibbs
  • gibbs
go to tiger-algebra.com
MrNood
  • MrNood
a = the answer is not 2 b I am not giving you the last step because you are studying maths and the best way to learn is to DO just do what I gave you above work out the area of the sides, and then add the area of TWO ends
gibbs
  • gibbs
it shows you how to do it and it gives the answer
MrNood
  • MrNood
OR do a little work and feel a little self satisfaction and pride
anonymous
  • anonymous
k
anonymous
  • anonymous
nonon
anonymous
  • anonymous
i meant lead me to the last step
MrNood
  • MrNood
I have led you all the way: here it is again - you just need to make 1 step from here... you do not know how many edges there are but if they were of lenght a,b,c,d .... etc then the area of 1 side would be 8a, then 8b + 8 c etc 8a+8b + 8c +...... = 8(a+b+c+......) but you know that the sum of (a+b+c+....) = 20 so there is the answer to the area of the sides
anonymous
  • anonymous
it can only be 2.5 or 2.4
anonymous
  • anonymous
3 is the answer
MrNood
  • MrNood
|dw:1449755063343:dw|
anonymous
  • anonymous
i get it the closest answer is 3
MrNood
  • MrNood
you have not posted any options
anonymous
  • anonymous
there is no option
MrNood
  • MrNood
so - if the area of just 1 end is 21 HOW can the total be 3?
anonymous
  • anonymous
7
welshfella
  • welshfella
The total area of the sides of the prism = perimeter of the base * height (8)
anonymous
  • anonymous
=20
MrNood
  • MrNood
I have told him that several times above - he is not even beginning to think about this I'm out
anonymous
  • anonymous
i don't get it
anonymous
  • anonymous
it is 2.5
anonymous
  • anonymous
@Demonx341
anonymous
  • anonymous
@Englishguy
anonymous
  • anonymous
@Demonx341
anonymous
  • anonymous
@gibbs http://tiger-algebra.com/ does not help
gibbs
  • gibbs
fine check here http://www.mathpapa.com/algebra-calculator.html
MrNood
  • MrNood
@super123 do you want to understand this?
anonymous
  • anonymous
no
anonymous
  • anonymous
@welshfella @Willie579 @Wendy.Ivette11714 @wwhitlock @Ephemera @Emiwock @Englishguy @ethan726 @explicitvogue @They_Call_Me_Narii @the_ocean_girl @TypnoEchosis @Theanitrix @twister02 @YoungStudier @YumYum247 @you_me @yb1996 @Yuna123 @UsukiDoll @uybuyvf @IloveHW @izzyrawrz @INeedYourHelpBad @I_Ask_Alot @IHelpYouLearn @Owlcoffee @okdutchman7 @otaylor19 @oreolo @phi @poopsiedoodle @puppylover52 @PenguinRulez @popcornfun @Astrophysics @AloneS @Anaise @AbdullahM @ash_heather1 @secret66 @sweetburger @seb.cal @DLS @Daniellelovee @Destinycholie @Deadly_Roses @dakid88 @DariusX @FortyTheRapper @flamingpiano @fashionguru12 @green_1 @gibbs @G@girlmeetsworld @gracea @HELP!!!! @HELLOMYNAMEISKAM @HS_CA @hoots89 @helpppppppppp @jameskang1015 @jebonna @jakyfraze @jordanpipes @jacobyoungbleed @♪Chibiterasu
welshfella
  • welshfella
imagine that the prism has no end bases and its made of thin cardboard if we cut vertically down the length and spread it out it would look like the following |dw:1449756104192:dw|
anonymous
  • anonymous
160
welshfella
  • welshfella
- rectangular piece of cardboard are 8 * 20 = 160 cm2 in area agreed?
anonymous
  • anonymous
k
welshfella
  • welshfella
yes so you just add on the areas of the 2 bases ( 2 times 21) and you have your answer
anonymous
  • anonymous
320
anonymous
  • anonymous
6720
welshfella
  • welshfella
No 160 + (2 times 21) = ? do the multiplication first
anonymous
  • anonymous
202
anonymous
  • anonymous
is it
anonymous
  • anonymous
@welshfella
welshfella
  • welshfella
yes 202 cm2 is correct
anonymous
  • anonymous
that is the answer
welshfella
  • welshfella
that is the answer
anonymous
  • anonymous
a medal 4 u and i will make a new ?
anonymous
  • anonymous
k
welshfella
  • welshfella
ok
welshfella
  • welshfella
The assumption that the base is a rectangle can be made and the method of solving the system of equations will give the correct solution though it is a more involved method than the above.
MrNood
  • MrNood
@welshfella The fact is the answer is the same for ANY base shape from 3 to n sides you cannot 'assume' that the answer for 4 sides is true for ALL - but it IS true that the answer for ALL (as I gave) IS true for your assumption of rectangle. There is nothing in the question to say rectangle - so you are likely to make a mistake if you assume things that are not given
welshfella
  • welshfella
I was merely saying that the answer will be the same if you assume that the base is a rectangle.

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