The file format can typically be identified by its file extension, which appears after the last dot in the file name. It indicates the type of file and determines which program should be used to open it. For example:
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.