(Jimmy of the Clue Crew presents the clue on the monitor.)  A pair of angles that  add together to make a straight line are called this type of angle
[DOC] [TLE] NASA's Hubble, Chandra Find Clues that May Help Identify Dark ... [PAR] Mar 26, 2015 ... NASA's Hubble, Chandra Find Clues that May Help Identify Dark Matter ... times 
and were viewed from different angles -- some from the side, and others head-on.