Question

With a ruler and compass which of the following angles cannot be constructed?

${60}^{\circ }$, ${80}^{\circ }$, ${90}^{\circ }$, ${105}^{\circ }$

• A. 80°
• B. 60°
• C. 90°
• D. 105°

Answer 1

The correct option is A

80°

With ruler and compass we can construct ${15}^{\circ }$, ${30}^{\circ }$, ${45}^{\circ }$, ${60}^{\circ }$, ${90}^{\circ }$, ${105}^{\circ }$ and so on. We cannot construct ${80}^{\circ }$ as it is not multiple of 3.