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| Question 1045545:  show in a new way that the points (-1 -2), (5 4), (-3 0) are the vertices of a right triangle
 Found 3 solutions by  ikleyn, blaser411, robertb:
 Answer by ikleyn(52879)
      (Show Source): 
You can put this solution on YOUR website! . 
 
1.  Calculate the length of each of the tree sides of the triangle, using the formula for the distance between the points in a coordinate plane.
2.  Then check that the square of the longest of the three sides is the sum
    of squares of the two other sides (Pythagorean equality).
I don't know what the words "in a new way" mean in this context.
 
 
Answer by blaser411(1)
      (Show Source): Answer by robertb(5830)
      (Show Source): 
You can put this solution on YOUR website! A vector associated with the points (-1,-2) and (5,4) is < 5--1, 4--2 > = < 6, 6 >. A vector associated with the points (-1,-2) and (-3,0) is < -3--1,0--2 > = < -2,2 >.
 Two vectors are perpendicular (or orthogonal) if their dot product is 0,
 < 6,6 >*<-2,2 > = -12 + 12 = 0.
 This, however, is not a new way, just a little level higher.
 Another way of showing this perpendicularity, but still not a "new" way, just a level lower, is
 getting the slope of the line passing through (-1,-2) and
 (5,4) and comparing this with the slope of the line passing through (-1,-2)
 and (-3,0).
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