# Tick the correct answer and justify : In $$\triangle$$, AB = $$6\sqrt{3}$$ cm, AC = 12 cm and BC = 6 cm. The angle is : (i) 120 (ii) 60 (iii) 90 (iv) 45

## Solution :

In triangle ABC, we have :

AB = $$6\sqrt{3}$$ cm , AC = 12 cm

and BC = 6 cm

Now, $${AB}^2$$ + $${BC}^2$$ = $$(6\sqrt{3})^2$$ + $$(6)^2$$

= $$36 \times 3$$ + 36 = 108 + 36 = 144 = $$(AC)^2$$

Thus, triangle ABC is a right angled triangle at B.

$$\therefore$$  $$\angle$$ B = 90