Question

In AABC, AB = 15 cm, AC = 18 cm and AD is perpendicular to BC so that AD = 12 cm. Find the length of BC.​

Answer 1

Answer:

Here BC = BD + CD

Therefore

From the above diagram we can say

By Pythagoras thereom ...

AB^2 = A D^2 + B D^2

15^2 = 12^2 + BD^2

225 -144 = BD^2

BD = √81

BD = 9cm

Now again

AC^2 = A D^2 + CD^2

18^2 = 12^2 + CD^2

CD = √324-144

CD = √180

CD = 13.41cm

NOw

BC = BD +CD

BC = 9+13.41

BC = 22.41cm

Answer = 22.41cm