Answer:
120°, 240°
Step-by-step explanation:
An equilateral triangle has 3 equal sides and 3 equal angles.
To rotate the equilateral triangle onto itself, we have to rotate each of those sides to an adjacent side. This happens when the angle of turn is [tex]\frac{1}{3}[/tex]th of a full-circle turn.
A circle has [tex]360^{\circ}[/tex] and [tex]\dfrac{1}{3}\times 360^{\circ}=120^{\circ}[/tex].
Therefore, a 120° rotation clockwise or counterclockwise puts each of the edges over the position where an adjacent edge was located.
Any angle which is a multiple of 120° will also do the same. So the answers should be 120°, 240°.
