Scale Drawings (Copy)

Scale Drawings and Bearings Cheat Sheet (IGCSE Mathematics 0580 – CORE)
Topic: Scale Drawings and Three-Figure Bearings

1. Scale Drawings

• Scale drawing: A drawing where all lengths are in proportion to real-life measurements using a given scale.
• A scale shows how measurements on the drawing relate to actual measurements.

Common examples:

• 1 cm represents 1 m (scale 1:100)
• 1 cm represents 10 km (scale 1:1,000,000)

Important points:

• Use a ruler for all straight lines.
• Measure carefully to match the scale.
• Label key distances clearly.

Example:
If scale is 1 cm = 2 m and a wall is 6 m long in real life:

• On the drawing, wall length = 6 ÷ 2 = 3 cm.

2. Bearings

• A bearing is a direction measured clockwise from north.
• Bearings are always given as three figures (e.g., 025°, 145°, 270°).
• North is 000°, East is 090°, South is 180°, West is 270°.

Rules for Bearings:

• Always measure clockwise from North.
• Always use three digits.
• Bearings range from 000° to 360°.

Example:

• Due East bearing = 090°
• Due South bearing = 180°
• Due West bearing = 270°
• Due North bearing = 000°

3. Important Bearings Interpretations

4. How to Find Bearings Between Two Points

Finding the bearing of A from B:

• Imagine standing at B and measuring clockwise to A.

Important note:

• Bearing of A from B and bearing of B from A are not the same unless exactly north-south or east-west aligned.

Example: If bearing of B from A is 025°, then bearing of A from B = 025° + 180° = 205°.

5. Tips for Drawing Bearings

• Draw a North line from the starting point.
• Use a protractor to measure the angle clockwise from North.
• Mark the direction with an arrow after measuring the angle.

This covers CORE-level requirements: drawing accurately to scale, interpreting and drawing bearings, using a ruler and a protractor carefully without requiring complex construction proofs.