SOLUTION: show that the points(4,0),(2,1),(-1,-5) are the vertices of a right triangle and find its area.

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Question 1016825: show that the points(4,0),(2,1),(-1,-5) are the vertices of a right triangle and find its area.
Answer by ikleyn(52829) About Me  (Show Source):
You can put this solution on YOUR website!
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show that the points (4,0), (2,1), (-1,-5) are the vertices of a right triangle and find its area.
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This is your triangle.




Calculate the distances between the given points (4,0), (2,1), (-1,-5).

1. Points (4,0) and (2,1). The distance a = sqrt%28%284-2%29%5E2+%2B+%280-1%29%5E2%29 = sqrt%282%5E2+%2B+1%5E2%29 = sqrt%285%29.

2. Points (2,1) and (-1,-5). The distance b = sqrt%28%282-%28-1%29%29%5E2+%2B+%281-%28-5%29%29%5E2%29 = sqrt%283%5E2+%2B+6%5E2%29 = sqrt%289+%2B+36%29 = sqrt%2845%29.

3. Points (4,0) and (-1,-5). The distance c = sqrt%28%284-%28-1%29%29%5E2+%2B+%280-5%29%5E2%29 = sqrt%285%5E2+%2B+5%5E2%29 = sqrt%2825+%2B+25%29 = sqrt%2850%29.

Now you see that a%5E2 + b%5E2 = 5 + 45 = 50 = c%5E2.

It is just enough to conclude that the triangle is right-angled.

Next, the area of the triangle is %28a%2Ab%29%2F2 = %28sqrt%285%29%2Asqrt%2845%29%29%2F2 = sqrt%28225%29%2F2 = 15%2F2 = 7.5 cm%5E2.