spider and fly...

editedIn a rectangular room (a cuboid) with dimensions 30x12x12 , a spider is located in the middle of one 12x12 wall one foot away from the ceiling. A fly is in the middle of the opposite wall one foot away from the floor. If the fly remains stationary, what is the shortest total distance (i.e., the geodesic) the spider must crawl along the walls, ceiling, and floor in order to capture the fly?

sorry...the picture was also given...this can help..

source wolfram....

29 Answers

49
Subhomoy Bakshi ·

yea i thnk give final hint!!

11
SANDIPAN CHAKRABORTY ·

FOR MORE DETAILS REGARDING THIS PROBLEM.....

(TO VIEW THE SPIDERS PATH ALONG THE CEILING,WALL,FLOOR,WALL.....IN ANIMATION...)

PLEASE SEE

http://mathworld.wolfram.com/SpiderandFlyProblem.html

11
SANDIPAN CHAKRABORTY ·

yup 40 is the correct answer.....[1]

[1][1][1][1]!!!!![1][1][1][1]

1
Kalyan Pilla ·

Calc mistake in #25

1
Kalyan Pilla ·

There are two other possibilities of squares at right
Numbered them

The first one gives a length of √1658 feet

and the second one gives 40 feet

So, the smaller, 40 feet is the answer right!!!!

hope, I made it

[339]

11
SANDIPAN CHAKRABORTY ·

no.. greater than this!![4]

1
Kalyan Pilla ·

The answer is √1480 right??

1
Kalyan Pilla ·

Think I found it............ Dont post the soln!!!!

11
SANDIPAN CHAKRABORTY ·

the question asks shortest path... the path you have chosen is not the shortest one....

there is even a shorter path possible...

the flaw lies in chosing your diagram...

theres another way to construct the cube....

you are veryy close!!! [1][1]

1
Kalyan Pilla ·

This is the figure U R sPkin about..............

Well, actly there R two short paths, wen U convert it to 2D, U can take the spider to move along the base or along the wall............
wen it moves along the wall, the distance covered is √(42)2+102 = √1864 feet

and wen it moves, along the base(ground/roof), the distance travelled is 42feet = √1764

The shorter of the two is the answer=42 feet
U can make the same room, using many kinds of card boards, it just depends which one u choose
[339]

11
SANDIPAN CHAKRABORTY ·

your figure is wrong....

think you are outside the room......

also think that you are given a cardboard...you are

to make a cuboid..... you don have glue... how would

you cut the cardboard??? in the same way open up the

given cardboard...and solve... you will get your answer...

1
Kalyan Pilla ·

Here z my method

This gives 42, and 42 is less than √1864
So, √1864, is surely not the answer[12][12]

[339]

1
Kalyan Pilla ·

That was wat I did, but I got 42[11][7]

49
Subhomoy Bakshi ·

it comes √1864...i did like tht initially!!

11
SANDIPAN CHAKRABORTY ·

@sb... try with #7 (govind's method..)

lets wait and see what other's have to say

49
Subhomoy Bakshi ·

is it 10√10

11
SANDIPAN CHAKRABORTY ·

ok should i give the final hint.... or wait for some more answers??

@govind: you are going wrong somewhere.....

29
govind ·

see for my first answer i posted my method...for the second one..the spider will move 1m abv and then 30m horizontal and 11m down towards the fly..or do it the other way that the spider moves 11m down first then 30m and then 1m...both will give the same answer 42m...

11
SANDIPAN CHAKRABORTY ·

no...... you are all too close...

can any 1 of you post ur method...

@sb : may be.... so whats the smallest...

49
Subhomoy Bakshi ·

well it is according to me 2nd smallest

49
Subhomoy Bakshi ·

3 rd try!! 48??

49
Subhomoy Bakshi ·

hmm...42 yes!!

11
SANDIPAN CHAKRABORTY ·

yup.. the sum was done by somewhat this method only.... so what answer you are getting.. by this method

@ govind...very close...not exact answer

29
govind ·

kk...second try...is it 42m..?

29
govind ·

well the way of doing this question is this..just assume the conditions given here..in the room u r sitting..(provided u r sitting in a rectangular room)..then just draw the conditions given on a paper..i mean convert the 3d structure into one..by making all the walls lie in the same plane and then just join the points between which u want to find the distance..then simple use of pythagoras theorem and it's done...

11
SANDIPAN CHAKRABORTY ·

nope....thats wrong..

ans is a two digit number...

29
govind ·

ya it's √1864...

49
Subhomoy Bakshi ·

ans is: √1864..if there is no calculation error!!

49
Subhomoy Bakshi ·

sorry i was wrong!![2][2]

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