Which of the following angles cannot be constructed using ruler and compass only ?

Below angles can be drawn using following


120° = 90° + 30° or 60° + 60° (where 30° is the bisected angle of 60° )


135°= 90° + 45°


37.5° is the bisected angle of 75° and 75° can be drawn using 90° and 60°.


But 40° cannot be drawn.

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