Maximum Area (1 Viewer)

[annabackwards]

I came across this question while studying some 3U and there are no solutions so i have no idea where to start.

Any help would be greatly appreciated

 

[azureus88]

You find y in terms of x and then do the usual differentiation thing.

so x/(12-y) = 16/12 (by letting AB=16 and BC=12, works the other way around as well)

x/(12-y) = 4/3

3x=48-4y

y=(48-3x)/4

A = xy = (48x-3x^2)/4

then differentiate

 

[Drongoski]

You find y in terms of x and then do the usual differentiation thing.

so x/(12-y) = 16/12 (by letting AB=16 and BC=12, works the other way around as well)

x/(12-y) = 4/3

3x=48-4y

y=(48-3x)/4

A = xy = (48x-3x^2)/4

then differentiate

or A = 3[x(16-x)]/4 a upside-down quadratic with zeros 0 and 16.

Max occurs at the mid-pt of these 2 zeros; i.e. at x = 8

when x=8, y= 3(16-x)/4 = 3(16-8)/4 = 6

Therefore dimensions for max area rectangle are 8 x 6 and area 48 square units.

 

[Aquawhite]

Since when do you need MX1 help Anna?

I've done this question before!... I needed a small kickstart, but I got it. Once you see what is done, it's actually very very basic.

 

[annabackwards]

^
Thanks guys for the help

I thought of doing that but then why'd they'd tell us that is a triangle in the corner? Unless that was just there to confuse me >.>

 

[Aquawhite]

^
Thanks guys for the help

I thought of doing that but then why'd they'd tell us that is a triangle in the corner? Unless that was just there to confuse me >.>

Maths is not meant to confuse us on purpose? :O

 

[annabackwards]

Maths is not meant to confuse us on purpose? :O

True, not generally but gah i hate questions without answers >.>

 

[Aquawhite]

True, not generally but gah i hate questions without answers >.>

It makes life hard... >_< Especially high end Ext.1 questions, they suck without a good solution.

 

[annabackwards]

It makes life hard... >_< Especially high end Ext.1 questions, they suck without a good solution.

Yupo.

But is the triangle really irrelevant to the question? oO

 

[clintmyster]

LOL thats why you do ones with answers! Surely you have more with answers?!

 

[annabackwards]

LOL thats why you do ones with answers! Surely you have more with answers?!

Yeah i do, but i can't find another question similar to this one in another paper with answers. I can't believe the paper this question came out of had answers for everything BUT this question :rofl:

 

[Aquawhite]

No, because they give you the dimensions of something that it fits perfectly into. Adding the name of another shape probably just fooled you XD

 

[annabackwards]

No, because they give you the dimensions of something that it fits perfectly into. Adding the name of another shape probably just fooled you XD

Ahaha ok. Thanks for the help guys

 

[random-1005]

^
Thanks guys for the help

I thought of doing that but then why'd they'd tell us that is a triangle in the corner? Unless that was just there to confuse me >.>

you use similar triangles and the ratio of sides, once again 4 unit people need help with 2 unit, disgraceful

 

[Aquawhite]

you use similar triangles and the ratio of sides, once again 4 unit people need help with 2 unit, disgraceful

This has been posted in the MX1 forums. I assume it's an MX1 question.

 

[random-1005]

This has been posted in the MX1 forums. I assume it's an MX1 question.

no 2 unit i have seen a question like this as a Q8 in a 2 unit paper, however it was in parts following you through the question e.g.

parta. Show that the triangles are similar
partb. Hence find the max area

but a 4 unit person getting stuck on this question, hilarious

 

[annabackwards]

Thanks for the back up guys

And for your information, this was from a 3U paper and it's not 2U becauce in 2 unit they never ask you anything like this with different shapes ie they only ask you for a shape within anotehr similar shape, not a rectangle in a triangle.

Leave my Anna out of this bitch! >_< Sorry that not everyone is as awesome as you.

you fail.

<3

 

[random-1005]

Thanks for the back up guys

And for your information, this was from a 3U paper and it's not 2U becauce in 2 unit they never ask you anything like this with different shapes ie they only ask you for a shape within anotehr similar shape, not a rectangle in a triangle.


<3

a bloody easy 3 unit paper, what was it, Q1??:rofl:


why wouldn't they, they can do whatever they like, its all within the 2 unit syllabus, and the methods are the exact same.

 

[Lukybear]

Did any1 somehow, could find the minimum area as well? Thats really weird as Ive never seen anything like this.

Thanks for the question Anna.

 

[clintmyster]

Did any1 somehow, could find the minimum area as well? Thats really weird as Ive never seen anything like this.

Thanks for the question Anna.

Oh yeah what paper was it?