To remove a stain, the first step is to act quickly and remove the stain when it is fresh. After that, soak the stain in cold water to loosen it. Then, soak it in warm soapy water for further cleaning, and finally expose it to sunlight to help remove any remaining marks.
In the adjoining figure, $\triangle CAB$ is a right triangle, right angled at A and $AD \perp BC$. Prove that $\triangle ADB \sim \triangle CDA$. Further, if $BC = 10$ cm and $CD = 2$ cm, find the length of AD.