In the given figure BA is parallel to CD, . AB = 10cm, BC= 9cm, AC=15cm. What is the length of AD?I tried solving with AB/BC = AD/AC. The answer turned out to be wrong because the solution in the book is given as,
Since ABC is similar to CAD, therefore, AB/BC = AC/AD.
I did not understand why they considered CAD instead DAC and AB/BC = AC/AD accordingly.