The pythagorean theorem holds for every right triangle: given the legs 
and the hypothenuse 
, the triangle is right if and only if
So, you have to check:
So the first triangle can't be a right triangle.
So the second triangle is a right triangle.
The third triangle can't be right, because it has the same legs but a different hypothenuse
Finally, we have
So the last triangle can't be a right triangle.
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5+5
7+3
9+1
8+2
2+8
4+6
6+4
10+0
all these equal 10
to isolate k, you have to divide 3/2 by 9/10. you will then get 5/3
