Thursday, December 25, 2008

Minimize triangle area

A right triangle, shown below,the right angle at origin. What are the dimensions of x and y such that the hypotenuse passes thru point (2,5) and the triangle area is minimized.


Another Image (click)

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15 Comments:

Anonymous Anonymous said...

x=4, y=10

December 25, 2008 10:25 AM  
Anonymous Anonymous said...

is this your homework?

December 25, 2008 1:24 PM  
Anonymous Anonymous said...

lol
if this is your homework, gj
pretty basic optimization problem

December 25, 2008 2:27 PM  
Blogger Ragknot said...

No, it's not my homework, but many years ago it might have been an assignment I made to students.

Now it should be a challenge to many who care to accept it. Too many nowdays can't think of any way to solve it.

December 25, 2008 7:02 PM  
Blogger Rajesh Lal said...

this is really a challenging problem.

December 25, 2008 9:11 PM  
Anonymous Bre said...

Ragknot,
you made a mistake. the picture is ABOVE the words, not below them. :)

December 25, 2008 10:58 PM  
Anonymous Bre said...

Oh, and I also meant to say that I agree with you, Rajesh. This is a tough question.

:)
:)
~Bre

December 25, 2008 11:01 PM  
Anonymous Anonymous said...

First reply above is right.

If the "top" of the triangle on the y axis is, say, at 5+n then we find that the rightmost point on the x axis is at 2+10/n.

So the area xy/2 = (5+n)(2+10/n)/2
or 10+n+25/n

This has a minimum where n = 5,
i.e. y = 10 and x = 4.

December 25, 2008 11:21 PM  
Anonymous Anonymous said...

The previous was right at
to the "Area = 10n+25/n."
Next could have been the derivative of that would be
A(n)=1-25/n^2
0=1-25/n^2
1=25/n^2
and solving... n = 5

December 26, 2008 1:13 AM  
Anonymous Corbin said...

x = 5
y = 8

December 26, 2008 10:54 AM  
Anonymous Anonymous said...

This post has been removed by a blog administrator.

January 16, 2009 5:38 AM  
Anonymous Anonymous said...

This post has been removed by a blog administrator.

January 16, 2009 5:38 AM  
Anonymous Anonymous said...

Those are very very very pretty pictures. But, they are very boring.

January 16, 2009 5:38 AM  
Anonymous Anonymous said...

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November 22, 2009 5:44 AM  
Anonymous Anonymous said...

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December 18, 2009 3:08 PM  

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