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Mathematics 16 Online
OpenStudy (anonymous):

medal-*Question in pic file*

OpenStudy (anonymous):

@xapproachesinfinity can u plz help? :)

OpenStudy (xapproachesinfinity):

did you try anything?

OpenStudy (anonymous):

no @sleepyjess

OpenStudy (xapproachesinfinity):

http://prntscr.com/6b74cn this the wanted triangle thinking ....

OpenStudy (xapproachesinfinity):

looks like a pyramid!

OpenStudy (anonymous):

lol! finding the volume

OpenStudy (xapproachesinfinity):

oh i take it back it is definitely a prism

OpenStudy (anonymous):

volume of prism

OpenStudy (xapproachesinfinity):

there is one missing puzzle the length of the prism haha

OpenStudy (xapproachesinfinity):

the volume of the prism is Area of the base time length

OpenStudy (displayerror):

What about integrating? Take the cross section to be perpendicular to the x-axis.

OpenStudy (anonymous):

@DisplayError yes! can u plz show me? :)

OpenStudy (xapproachesinfinity):

oh i got it since the cross sections are square and one side the hypotenuse of the triangle

OpenStudy (xapproachesinfinity):

so the hypotenuse is \[\sqrt{72}\]

OpenStudy (anonymous):

kk

OpenStudy (xapproachesinfinity):

oh actually i like what Dis mention we take the cross section perpendicular to x axis that's much better

OpenStudy (xapproachesinfinity):

so side of the square are 6 now we have got everything needed

OpenStudy (xapproachesinfinity):

so just do 1/2 6^3

OpenStudy (displayerror):

I would solve the equation of the line \(y = -x + 6\) and take that to be one side of the cross section. Since the cross section is a square, the area of the cross section would be \(\left(-x + 6\right)^2\), then integrate that from 0 to 6.

OpenStudy (xapproachesinfinity):

hmmm that would make the solid a pyramid not a prism

OpenStudy (xapproachesinfinity):

unless if you did what i did above the hypotenuse to be one side of the cross section

OpenStudy (xapproachesinfinity):

but i realized that won't work so i used what you mentioned about the cross section being perpendicular to x axis which make it easier to solve

OpenStudy (xapproachesinfinity):

this way you have all you want the area of the base (1/2 6^2) the length of the prism 6

OpenStudy (anonymous):

@DisplayError i think it would be: D, 72

OpenStudy (xapproachesinfinity):

i found 108

OpenStudy (anonymous):

@xapproachesinfinity lol can u plz write out the steps

OpenStudy (anonymous):

@DisplayError do u say its 108

OpenStudy (xapproachesinfinity):

everything is under you noise why are you lazy i feel like you are not paying attention to what we are doing heheh

OpenStudy (anonymous):

i integrated what @DisplayError

OpenStudy (displayerror):

Integrating I get 72. But perhaps that isn't the correct procedure to solve this problem?

OpenStudy (xapproachesinfinity):

hmm you are integrating with respect to what?

OpenStudy (anonymous):

(-x+6)^2 with upper limit 0 & lower limit 6

OpenStudy (displayerror):

I'm assuming the cross section is perpendicular to the x-axis, so \(dx\).

OpenStudy (anonymous):

to be honest i got -72

OpenStudy (xapproachesinfinity):

but that won't give the volume will it?

OpenStudy (xapproachesinfinity):

oh hold on

OpenStudy (displayerror):

We're integrating \(\int \text{Area} \ dx\), so units of \(\text{length}^2 \times \text{length} = \text{length}^3\)

OpenStudy (xapproachesinfinity):

i'm not worried about the units i'm thinking about the increment you have used

OpenStudy (xapproachesinfinity):

don't you think that if the cross section is perpendicular to x axis we don't have \[(-x+6)^2\] or may be i'm thinking about something different here lol

OpenStudy (anonymous):

!

OpenStudy (anonymous):

lets skip

OpenStudy (anonymous):

OpenStudy (displayerror):

The cross sections are squares, so the area of the cross section would be given by \(\text{side}^2\). The length of one side of the square is given by \(y = -x + 6\) (assuming the cross section is perpendicular to the x-axis).

OpenStudy (anonymous):

OpenStudy (xapproachesinfinity):

yeah but you made the cross section be perpendicular to x axis so you don't have that

OpenStudy (anonymous):

i found--> http://www.math.ttu.edu/~drager/Classes/04Fall/m1352/anspract1.pdf page 3

OpenStudy (displayerror):

Okay, let's take the cross section to be perpendicular to the y-axis, then we have \(x = 6 - y\) and we can integrate with respect to y from y = 0 to y = 6, which would still lead to a volume of 72 cubic units.

OpenStudy (anonymous):

thank u!!!

OpenStudy (anonymous):

OpenStudy (anonymous):

OpenStudy (xapproachesinfinity):

what is the deal with you mathrulezz still doing that other problem? y=x^2, x=4 y=1? i thought you are done with that one the point is not to get fancy grades the point is you understand what you are doing

OpenStudy (xapproachesinfinity):

after reflecting on it i think you are right @DisplayError i was thinking about something different in mind

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

only 1 left

OpenStudy (anonymous):

either A, B, or C

OpenStudy (anonymous):

would it be: C

OpenStudy (anonymous):

@DisplayError

OpenStudy (anonymous):

actually D

OpenStudy (anonymous):

hello

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