Mathematics

Problem

\triangle ABC

, point

D

lies on

AB

. Suppose

\angle ACD = \angle DBC

and

\angle ADC = \angle DCB

. Given

AD = 10\,\text{cm}

BD = 9\,\text{cm}

and

DC = 6\,\text{cm}

, find the length of

BC

. a)

7.5\,\text{cm}

5.4\,\text{cm}

3.6\,\text{cm}

6.4\,\text{cm}