\(ABCDEFGHIJ\) is a regular decagon. The rotation centered at \(G\) with an angle of alpha takes \(D\) to \(J \). Given that alpha is less than 180 degrees, find alpha.

Thank you!

I don't know why the latex isn't working.

alpha = 84 degrees.

I am not sure about the process, could you share some of your thought process? Thanks!

As follows:

Thank you so much! I get the answer now.