Alicia draws an equilateral triangle and then rotates it about its center. Through which angle measures can she rotate the equilateral triangle to map it onto itself?
An equilateral triangle has 3 lines of symmetry, but of more importance in this case, it has rotational symmetry of order 3. This means that in a rotation of 360° the same image appears 3 times.
The triangle rotates through the exterior angle so that the next vertex can be in the same position as the previous one.
IN the same way, a square will rotate through
A pentagon will rotate through