What can I do about an unjustified speeding ticket?

I was driving today on I70 79mph when a state trooper named Boone stopped me claiming he recorded me at 85 I was stunned at 1st as I was for 30 miles driving on cruise control on 79(Speed limit is 75) My car is Cadillac DTS 2011 had 15000 miles and was at the shop for check 1 week ago .I tried to convince him he was wrong to no avail was afraid of him but was tempted to ask him to show me his radar reading .If I had that speed I would pa y the $170 ticket