Question

What is the third number which can form a Pythagorean triplet along with 9 and 12?

• A. 15
• B. 21
• C. 3
• D. 108

Answer 1

The correct option is A 15

A Pythogorean triplet is a set of three positive integers a,b and c, which follows the rule
$a^2+b^2=c^2.$
In the above given numbers, 9 and 12, if $a=9$ and $b=12,$ then
we can observe that
$9^2+{12}^2=81+144=225={15}^2.$
Hence, the condition for a Pythagorean triplet is satisfied, if the third number is 15.