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Math II-A 2.25

 
 
Picture of Eric Duan
Math II-A 2.25
by Eric Duan - Saturday, December 12, 2020, 9:16 PM
 

Question 2.25:

Consider the diagram below


How many of the rectangles in the diagram are NOT squares?


I know how to calculate the total number of rectangles in the figure but I’m not sure how to get the total number of squares. 

 
Picture of Duy Duong
Re: Math II-A 2.25
by Duy Duong - Sunday, December 13, 2020, 8:17 AM
 

I'd help you, but I can't see the diagram.

 
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Picture of Eric Duan
Re: Math II-A 2.25
by Eric Duan - Sunday, December 13, 2020, 7:42 PM
 

I figured it out:

Rectangulars: 7C2 x 6C2=315

Squares: side=1+side=2+side=3+side=4+side=5

                    6x5+5x4+4x3+3x2+2x1=70

315-70=245


 
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