Question

The numbers 20, 21, 29 form a Pythagorean triple. Which are other sets of numbers a Pythagorean triple?

21, 22, 30
40, 42, 58
60, 66, 87
70, 84, 116

Answer 1

an interesting propery of triplles is that if
a²+b²=c²
and a,b,c, is a tripple, then
ax,bx,cx is also a tripple when x=x

if we multiply 20,21,29 by 2 (mulitply all )
we get
40,42,58
that is 2nd option

answer is 2nd

Answer 2

The answer is 40, 42 and 58
40² + 42² = 58²