marcodonzelli wrote:

I see 1 and 2 are both insuff by theirselves. together: in order for the triangle to be rectangle we must have ab^2 + bc^2 = ac^2, where obviously ac must be the hypothenuse because it is greatest side. then we know that 145^145=21025. 17^2= 289 and 144^144=20736. 20736+289=21025, then OA is C. anyway, without doing any kind of calculus, by 1 and 2 we would know that it is possible to figure out whether ab^2 + bc^2 = ac^2, so c is suff

I'm very lazy, I see that the last digit of the square of 17 plusing the last digit of square of 144 produces a number that ends 5, which is the same as the last digit of square of 145. I conclude that ABC is right triangle at B. So I choose C

Is there any problem with my reasoning?

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