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find the length of the longer diagonal of a rhombus if the shorter diagonal is 12 and the perimeter is 36

 May 25, 2015

Best Answer 

 #1
avatar+128597 
+5

The diagonals form right angles......so we have

 

[(1/2) the shorter diagonal]^2 + [(1/2) the longest diagonal]^2  = [(1/4) perimeter]^2

 

6^2  + d^2  = 9^2      where d is 1/2 the length of the longer diagonal......so.....by the Pythagorean Theorem, we have

 

√[9^2 - 6^2]  = √[81 - 36 ] = √45  =  3√5 = d   ......   and twice this = 6√5 = about 13.416

 

 

 

 May 25, 2015
 #1
avatar+128597 
+5
Best Answer

The diagonals form right angles......so we have

 

[(1/2) the shorter diagonal]^2 + [(1/2) the longest diagonal]^2  = [(1/4) perimeter]^2

 

6^2  + d^2  = 9^2      where d is 1/2 the length of the longer diagonal......so.....by the Pythagorean Theorem, we have

 

√[9^2 - 6^2]  = √[81 - 36 ] = √45  =  3√5 = d   ......   and twice this = 6√5 = about 13.416

 

 

 

CPhill May 25, 2015

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