Question

∆ABC is an isosceles triangle with AB = AC = 13cm and the length of altitude from A on BC is 5cm. Then, BC = ? 

(a) 12 cm 

(b) 16 cm 

(c) 18 cm 

(d) 24 cm

Answer 1

(d) 24 cm

In triangle ABC, let the altitude from A on BC meets BC at D. 

We have: 

AD = 5 cm, AB = 13 cm and D is the midpoint of BC. 

Applying Pythagoras theorem in right-angled triangle ABD, we get:

Therefore, BC = 2BD = 24 cm