Question

Fig. 6.58
4. In Fig. 6.59, ABC is a triangle in which Z ABC < 90° and AD I BC. Prove that
AC2 = AB2+ BC2-2 BC.BD.
A​

Answer 1

Answer:

AC2 = AD2 + DC2

AD2 = AB2 - BD2

AC2 = AB2- BD2 + (BC - BD)2

AC2 = AB2 - BD2 + BC2 + BD2 - 2BC.BD

AC2 = AB2 + BC2 - 2BC.BD