## Geometry: Common Core (15th Edition)

a) $\angle Y$ b) right angles c) $m\angle Y$ d) $\angle X\cong\angle Y$
a) $\angle Y$ is the other angle in the given statement. b) Angles that measure 90 degrees are called right angles. c) If both angles measure 90, then the angles have equal measure. d) Since the measures of X and Y are equal, X and Y are congruent.