Question

Regular decagon ABCDEFGHIJ rotates 360° counterclockwise about its center. At which angle of rotation does A′ (the image of A) coincide with D?

36°

72°

108°

144°

Answer 1

Welcome to OpenStudy! I think I know what your talking about....Is it this picture??

Answer 2

Yes!

Answer 3

Sorry....you can't see it well...but.. We need to find what angle the vector A makes with the the vector D.

the central angle subtended by each side is (360/10)

the angle made by A' with vector D is 180-7*(360/10)

since the rotation is counterclockwise the angle you are looking for is 360-(180-7*(360/10))

Answer 4

So the answer is D?

Answer 5

Yup!:)

Answer 6

Thank you.

Answer 7

No problem!:)

Answer 8

D is wrong