Scale Drawings

4.3 Scale Drawings – Cheat Sheet

1. Scale Drawings

• A scale drawing is an accurate diagram of an object, reduced or enlarged proportionally.
• Scale = ratio of drawing length to actual length.

Example: Scale 1 : 200

• 1 cm on drawing = 200 cm (2 m) in real life.

Steps to Draw:

1. Decide scale based on object size and paper size.
2. Convert actual lengths to drawing lengths using scale.
3. Use ruler for straight edges, compass/protractor for angles.

Interpreting Scale Drawings:

• Convert measured length on drawing back to real length using scale.

2. Bearings

• Bearings = direction from one point to another, measured in 3-figure format (000° to 360°).
• Measured clockwise from North.
• Always write with three digits: 025°, 090°, 180°, 270°, etc.

3. Finding Bearings

Example 1: Bearing of A from B is 025°, find bearing of B from A

• Reverse direction → add/subtract 180°: 025° + 180° = 205° (if > 360°, subtract 360°).

Example 2: Point D is due east of C

• Due east = 090° bearing from C to D.
• Bearing from D to C = 270°.

4. Compass Directions and Bearings

5. Quick Reference Table