In a right-angled triangle ABC, ∠B = 90°. (i) If AB = 6 cm, BC = 8 cm, find AC. (ii) If AC = 13 cm, BC = 5 cm, find AB.

i) In ΔABC, ∠B = 90°
∴By Pythagoras theorem, AC² = AB² + BC²
AC² = 6² + 8²
∴AC² = 36 + 64 = 100
∴AC = 10 cm
ii) In ΔABC, ∠B = 90°
∴By Pythagoras theorem, AC² = AB² + BC²
13² = AB² + 5²
∴AB² = 169 - 25 = 144
∴AB = 12 cm