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ps - geometry

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ps - geometry

by ccassel » Tue Apr 19, 2011 12:13 pm
How would you solve this problem?

In a figure, two rectangles with the same dimensions overlap to form a shaded region (right angle triangle). If each rectangle alone has perimeter 12 and the shaded region has perimeter 3, what is the total length of the outside perimeter of the new shape?

A. 15
B. 18
C. 21
D. 22
E. 23

Answer is C
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by force5 » Tue Apr 19, 2011 12:24 pm
on second thought. the question can be done like this

Total perimeter = 24
overlapping is 3
now this overlapping can be done in many ways... but it doesn't matter because the question asks you the perimeter of remaining part.

consider these rectangles to be open threads in the form of circles. if i overlap 2 circles then the perimeter of remaining area will be total - overlapping.
hence the answer should be 21
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by ccassel » Tue Apr 19, 2011 2:08 pm
To expand on your answer...no new lines are created (only subtracted) therefore, the entire perimiter of the triangle will be subtracted from the entire perimeter of the square.
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