Question

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

• A. 80°
• B. 60°
• C. 90°
• D. 105°

Answer 1

The correct option is A

80°

With ruler and compass we can construct ${90}^{\circ }$, ${45}^{\circ }$, ${67.5}^{\circ }$ ${22.5}^{\circ }$, ${135}^{\circ }$ and so on. We cannot construct ${80}^{\circ }$ as it is neither a multiple or sub-multiple of ${45}^{\circ }$ nor a combination of them.