SOLUTION: Determine if the points (3,5), (3,3) and (2,4) are the vertices of a right triangle. Explain your rationale.

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Question 1195474: Determine if the points (3,5), (3,3) and (2,4) are the vertices of a right triangle. Explain your rationale.
Found 2 solutions by Alan3354, ikleyn:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Determine if the points A(3,5), B(3,3) and C(2,4) are the vertices of a right triangle. Explain your rationale.
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Slope of AC = diffy/diffx = (3-2)/(5-4) = 1
Slope of BC = ((3-2)/(3-4) = -1
---> perpendicular --> a right triangle

Answer by ikleyn(52865) About Me  (Show Source):
You can put this solution on YOUR website!
.
Determine if the points (3,5), (3,3) and (2,4) are the vertices of a right triangle.
Explain your rationale.
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Points A = (3,5) and B = (3,3) have the same x-coordinate.


It means that both points A and B lie on vertical line x= 3, parallel to y-axis.



Next,      points  A = (3,5) and C = (2,4)  have different y-coordinates; hence, line AC is not horizontal.

Similarly, points  B = (3,3) and C = (2,4)  have different y-coordinates; hence, line BC is not horizontal.



Thus, line AB is vertical, but angles A and B are not right angles.


So, we only should check if lines AC and BC are perpendicular.



Line AC has the slope  %284-5%29%2F%282-3%29 = %28-1%29%2F%28-1%29 = 1.

Line BC has the slope  %284-3%29%2F%282-3%29 = 1%2F%28-1%29 = -1.



Thus lines AC and BC are perpendicular, since their slopes are 1 and -1, i.e. negatively reciprocal 

     (their product is  1 * (-1) = -1).


ANSWER.  Angle C is the right angle.

Solved.