## Geometry: Common Core (15th Edition)

a) 90 b) 90 c) m$\angle3$ d) congruent
a&b) Complementary angles are defined as angles whose measures have a sum of 90. c) $m\angle1+m\angle2-m\angle2=m\angle3+m\angle2-m\angle2$ simplifies to $m\angle1=m\angle3$ d) Congruent angles are defined as angles with the same measure.