海島算經

''海島算經'' by active 3rd century-4th century Hui Liu is a mathematical treatise written during the early ancient period in China. This work primarily explores concepts of geometry and surveying, providing methodologies for calculating heights and distances through various practical problems. The content reflects the advancements in mathematical thought during this historical time. The book presents a series of problems related to surveying and measurement, utilizing visual observations and geometric principles to derive unknown quantities such as heights of islands, trees, and the dimensions of towns. For each scenario, it details a systematic approach to measurements, specifying how to align markers and employ calculations based on ratios derived from observed distances and heights. The solutions emphasize the use of simple multiplication and subtraction to arrive at precise measurements based on practical observations. Overall, ''海島算經'' serves as a foundational text, exemplifying the integration of mathematics with real-world applications in ancient China.