AB = 6√3 cm
⇒ AB2 = 108 cm2
AC = 12 cm
⇒ AC2 = 144 cm2
BC = 6 cm
⇒ BC2 = 36 cm
∴ AC2 = AB2 + BC2
Since, the square of the longest side is equal to the sum of two sides, so ∆ABC is a right angled triangle.
∴ The angle opposite to ∠90°
Hence, the correct answer is option (c)
