IGCSE CCEA Geography: Formula & Theorem Quick Reference Handbook | IGCSE CCEA 地理：公式定理速查手册

📚 IGCSE CCEA Geography: Formula & Theorem Quick Reference Handbook | IGCSE CCEA 地理：公式定理速查手册

This quick reference handbook compiles the essential formulas, ratios and decision rules needed for CCEA IGCSE Geography. It covers mapwork, population, settlement, rivers, coasts, weather and development. Use it alongside past papers and fieldwork tasks.

本速查手册汇编了 CCEA IGCSE 地理所需的核心公式、比率与判读规则，涵盖地图技能、人口、聚落、河流、海岸、天气与发展。请结合历年真题和野外考察任务使用。

1. Map Scale and Distance | 地图比例尺与距离

Map scale links a measurement on the map to the real distance on the ground. Always express distance in the same unit before converting.

地图比例尺将地图上的测量长度与实地距离联系起来。换算前必须先把单位统一。

For a written scale such as 1:50,000, every 1 cm on the map represents 50,000 cm on the ground. To convert to kilometres, divide by 100,000.

对于 1:50,000 这样的数值比例尺，地图上的每 1 厘米代表实地 50,000 厘米。要换算成公里，需除以 100,000。

Distance (km) = Map distance (cm) × Scale denominator ÷ 100,000

Example: on a 1:25,000 map, a road is 6.4 cm long. Real length = 6.4 × 25,000 = 160,000 cm = 1.6 km.

示例：在 1:25,000 地图上，一条道路长 6.4 厘米。实地长度 = 6.4 × 25,000 = 160,000 厘米 = 1.6 公里。

For curved distances, use a piece of string or paper edge, mark the route, then measure against the linear scale.

测量河流、道路等曲线时，可用细绳或纸边沿线路标记，再放到直线比例尺上读数。

2. Area Calculation on Maps | 地图面积计算

Map area calculations require you to convert map length and width into ground distances first. For regular features such as rectangular fields, multiply ground length by ground width.

地图面积计算要求先把地图上的长和宽换算成实地距离。对于矩形农田等规则地物，将实地长度乘以实地宽度。

Ground area (km²) = Ground length (km) × Ground width (km)

For irregular shapes, count full grid squares and add the area of partial squares. Each partial square is usually counted as 0.5 if more than half covered.

对于不规则图形，先统计完整方格，再加部分方格的面积。通常覆盖超过一半的部分方格按 0.5 计算。