Carrie has a 10-ft plank of wood. She wants to cut 3 pieces that are each 2 ⅔ feet long from the plank. How long will the plank be after she cuts off the three pieces?

2ft

Step-by-step explanation:

(3)2 2/3= 8

10-8 = 2ft left

geometry: triangles

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lessons

answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584