Question

If 21 and 35 are two members of a Pythagorean triple, what is the third member?

Answer 1

$\textsf{Let the pythagorean triplet be (a,b,c)=(21,x,35)}$

$\textsf{since (a,b,c) is a pythagorean triplet, we get}$

$\mathsf{c^2=a^2+b^2}$

$\mathsf{35^2=21^2+x^2}$

$\mathsf{1225=441+x^2}$

$\mathsf{1225-441=x^2}$

$\mathsf{x^2=784}$

$\mathsf{x=\sqrt{784}}$

$\mathsf{x=28}$

$\therefore\textsf{The third member of the triplet is 28}$