If a point is a midpoint then it divides the segment into two congruent segments.
if a ray bisects an angle then it divides the angle into two congruent angles.
if two points trisect a segment then they divide the segment into three congruent segments.
if two rays trisect an angle then they divide the angle into three congruent angles.
if two angles (or segments) have the same measure then they are congruent.
if two lines are perpendicular then they form a right angle.
if two angles sum to a right angle then they are complementary
if an angle measures between 0 degrees and 90 degrees then it is an acute angle.
if an angle measures between 90 degrees and 180 degrees then it is an obtuse angle.
if two angles sum to a straight angle then they are supplementary.
if an angle measures 90 degrees then it is a right angle.
if an angle measures 180 degrees then it is a straight angle.