Question 948015
If it's a right triangle, it follows the Pythagorean theorem,
{{{A^2+B^2=C^2}}}
Check all three.
I'll do the first.
{{{1^2+2^2=4^2}}}
{{{1+4=16}}}
{{{5=16}}}
False, so it's not a right triangle.
Now do the same for the remaining two.