This is an angle whose measure is between 0 degrees and 90 degrees. these are a pair of angles, adjacent or nonadjacent, whose sum is 90°. these are angles, segment, triangles etc. that have exactly the same measures. this is an angle having a measure greater than 90° and up to 180°. this is an angle whose measure is exactly 90°. two angles whose measures add up to 180 degrees. these are angles opposite one another at the intersection of two lines. these are two angles in a plane which share a common vertex and a common side but do not overlap. this is an angle with a measure of 180 degrees. this is the angle formed with you extend a side of the polygon. it is adjacent to the interior angle of the polygon.