Question

Regular pentagon ABCDE rotates counterclockwise about its center to yield pentagon A'B'C'D'E'. At which angle of rotation does A' coincide with D?

Answer 1

The total internal angle of a pentagon is 360. 360 is derived from the total angle of a circle. Pentagon has 5 sides. Rotating the pentagon counterclockwise, from point A and coincide with point D, it takes 3 turns. Divide 360 by 5. Multiply the quotient by 3. So, you will get 216 degrees.