Write the expression for the angle of contact in terms of interfacial tensions.

Explanation

To derive the expression for the angle of contact (also known as the contact angle) in terms of interfacial tensions, we can follow these steps:

### Step 1: Understand the Components
The angle of contact (θ) is defined at the interface where a liquid droplet meets a solid surface. The interfacial tensions involved are:
- \( t_1 \): Liquid-solid interfacial tension
- \( t_2 \): Solid-gas interfacial tension
- \( t_3 \): Liquid-gas interfacial tension (which can be considered as the tension between the liquid and the vapor above it)

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