The sides of four triangles are given below: (i) 20 cm, 22 cm, 24 cm (ii) 15 cm, 32 cm, 37 cm (iii) 11 cm, 60 cm, 61 cm (iv) 19 cm, 40 cm, 41 cm. Which of them forms a right triangle?

For a right triangle, the sum of squares of the two smaller sides must equal the square of the largest side. (i) 20² + 22² = 400 + 484 = 884 ≠ 576 (24²). (ii) 15² + 32² = 225 + 1024 = 1249 ≠ 1369 (37²). (iii) 11² + 60² = 121 + 3600 = 3721 = 61². ✓ (iv) 19² + 40² = 361 + 1600 = 1961 ≠ 1681 (41²). Only (iii) is a right triangle.