1. Let's understand the problem: you want to know how to derive or use a new formula when you don't know the originally given formula. 2. The key approach is to start from basic principles related to the problem instead of relying on a known formula. 3. Identify the quantities involved and the relationships between them that are fundamental and intuitive. 4. For example, if you are solving for distance, speed, and time, but don't know the formula $distance = speed \times time$, you can reason: - Speed means how much distance is covered per unit time. - Time is the total duration. So to find distance, you multiply speed by time, giving $distance = speed \times time$. 5. In algebra, if you don't know a formula, try to derive it by manipulating known equations, applying definitions, or experimenting with simple cases. 6. If the problem relates to geometry or physics, start with fundamental laws or postulates (e.g., Newton's laws, Pythagoras theorem) and build up. 7. Always write down what you know and what you want to find, then use logical steps and reasoning to connect these. 8. If stuck, try to express the unknown formula in terms of quantities you understand and use substitution or rearrangement techniques. Final advice: Understanding the underlying principles helps derive or find alternative formulas without prior knowledge of the given one.