Question

Which of the following angles cannot be constructed with a ruler and compass ?

• A. 80
• B. ${60}^{\circ }$
• C. ${90}^{\circ }$
• D. ${105}^{\circ }$

Answer 1

The correct option is A

80

With a ruler and compass we can construct ${15}^{\circ }$, ${30}^{\circ }$, ${45}^{\circ }$, ${60}^{\circ }$, ${75}^{\circ }$, ${90}^{\circ }$, ${105}^{\circ }$ angles. We cannot however construct an ${80}^{\circ }$ angle with a ruler and compass only. A protractor will also be required.