Homework Help: Pre-Algebra

Posted by Joy on Wednesday, March 5, 2008 at 10:35pm.

A triangle is enlarged by a scale factor of 10/3.

a) If the perimeter of the copy is 36 meters, find the perimeter of the original triangle using the proportion 10/3.

b) If the area of the copied triangle is 48 meters squared, use a proportion to find the area of the original triangle.

Please HELP me! I don't really know how I can solve this...

Pre-Algebra - Samantha, Thursday, March 6, 2008 at 1:10am
( copy/ orginal) = 10/3

(10/3)=(copy perimeter)/(orig.perimeter)
(10/3)=(36/X)
cross multiply and you get
10x=108 then x= 10 4/5 =10.8
x=perimeter of org.
triangle
Do the same with part b but this time it's area.
(10/3)=(48/x) ===> x= 14 2/5 =14.4
- Pre-Algebra(second part is wrong) - Reiny, Thursday, March 6, 2008 at 7:54am
  Samantha, your second part is not correct
  
  The area of similar figures is proportional to the square of their sides. Since perimeter is a function of the sides you last line should have been
  
  (10/3)² =(48/x) ===> x= 4.32

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