The four factors to consider when choosing the right method of communication are:
1. Audience: Consider who the message is intended for (peers, superiors, customers) and their preferred communication style.
2. Message Complexity: If the message is complex or requires detailed explanation, face-to-face or written communication may be preferable.
3. Urgency: For urgent matters, instant messaging or a phone call may be more effective.
4. Formality: Formal messages may require professional channels like email, while informal communications can be done through quick chats.
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.