Determine whether a triangle with the given vertices is a scalene, isosceles, or equilateral triangle. Check all that apply.

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  (a) isosceles

  (b), (c) scalene

Step-by-step explanation:

The lengths of the sides can be found from the distance formula:

  d = √((x2 -x1)^2 +(y2 -y1)^2)

Here, there are 9 lengths to be computed, so it is useful to let a spreadsheet or graphing calculator do it.

We find triangle (a) has two sides the same length, so it is isosceles.

The other two triangles have three different side lengths, so they are scalene.

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Additional comment

It is impossible to specify an equilateral triangle using rational coordinates.

geometry: triangles

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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

step-by-step explanation: