Answer
a) 90
b) 90
c) m$\angle3$
d) congruent
Work Step by Step
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.
