Which of the following sets of sides form a right-angled triangle?”

To check a right-angled triangle, we use the Pythagoras theorem:
$ a^2 + b^2 = c^2 $ (where $c$ is the largest side)

Option 1: 16 cm, 31 cm, 34 cm

$16^2 + 31^2 = 256 + 961 = 1217$
$34^2 = 1156$
❌ Not equal → Not a right triangle

Option 2: 12 cm, 16 cm, 20 cm

$12^2 + 16^2 = 144 + 256 = 400$
$20^2 = 400$
✅ Equal → Right-angled triangle

Option 3: 6 cm, 7 cm, 10 cm

$6^2 + 7^2 = 36 + 49 = 85$
$10^2 = 100$
❌ Not equal

Option 4: 5 cm, 11 cm, 13 cm

$5^2 + 11^2 = 25 + 121 = 146$
$13^2 = 169$
❌ Not equal

Final Answer:

12 cm, 16 cm, 20 cm ✔️