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Distance to the corner of a rectangle 
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#1
Nov2011, 07:15 AM

P: 100

1. The problem statement, all variables and given/known data
This question is taken from 2011 Malaysian Mathematical Olympiad. Mary is standing in a rectangular garden. Her distance to the four corners of the garden are 6 m, 7 m, 9 m and d m, respectively, where d is an integer. Find d. 2. Relevant equations Triangle inequality. a + b < c, a + c < b, b + c < a, where a, b, and c are the lengths of the three sides of the triangle. 3. The attempt at a solution I tried to denote the length of the rectangular garden as a and b, respectively, then from the four triangles formed, I formed some inequality and try to see if the value of d is bounded, but it yields nothing. I have also tried to solve for d by using the concept of area. Also, I tried using the law of cosine and the Pythagorean theorem. But still, I can't find the value for d. Any other ideas how to approach this problem? Thanks. :) 


#2
Nov2011, 07:41 AM

HW Helper
P: 1,347

Pythagorean Theorem is the way to go. Draw two perpendicular lines "through" Mary. You'll have four right triangles, with 6, 7, 9 and d being the hypotenuses. Use the Pythagorean Theorem four times, and through some manipulation, you'll be able to find d.



#3
Nov2011, 07:53 AM

P: 100




#4
Nov2011, 08:02 AM

HW Helper
P: 1,347

Distance to the corner of a rectangle
EDIT: I think I know why our answers differ. It depends on how you label the four distances from Mary to the corners. I took "6, 7, 9 and d, respectively" to mean that you label the line segments clockwise in that fashion. It looks like you labeled them as "6, 9, d and 7," going clockwise, or something similar. Are you looking at a diagram? 


#5
Nov2011, 08:10 AM

P: 100

[itex]v_{1}^{2}+h_{1}^{2}=6^2=36[/itex]
[itex]v_{1}^{2}+h_{2}^{2}=7^2=49[/itex] [itex]v_{2}^{2}+h_{1}^{2}=9^2=81[/itex] [itex]v_{2}^{2}+h_{2}^{2}=d^2[/itex] [itex]d^2=v{2}^{2}+h_{2}^{2}=13036=94[/itex] 


#6
Nov2011, 08:14 AM

P: 100

EDIT: No diagram was given for the question. 


#7
Nov2011, 08:24 AM

P: 100

Since the question says d is an integer, I try to use other types of 'combination', and when I tried with '6, 9, 7, d' going clockwise, I get d = 2. Yay! Thanks again, eumyang, for the help :)



#8
Nov2011, 08:28 AM

HW Helper
P: 1,347

I had forgotten about the "d is an integer" part when I last posted. I'm glad you got the answer.



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