Concept 6 of 10Foundation
Watch on YouTubeVideoConstructing standard angles
Without a protractor, you can construct:
- 60° — arc-based (equilateral triangle method).
- 90° — by bisecting a straight angle (180°).
- 30° — bisect a 60°.
- 45° — bisect a 90°.
- 120° = 60° + 60°.
Example
To get 75°: draw 90°, then inside it draw 60°; bisect the 30° gap to get 75° from the base arm.
💡 Tip:Learn to combine & bisect — you can hit most angles just with compass + ruler.
▶Prefer a video? Open YouTube search for “construct 30 45 60 90 angle without protractor”↗🎯 Try it!
5 questions to check what you just read.
0 / 5
- Q1.To get 30°, bisect:
- Q2.To get 45°, bisect:
- Q3.To get 15°, bisect:
- Q4.To get 120°, combine:
- Q5.75° can be obtained by: