see the attached figure to better understand the problem
we know that
∡A+∡B+∡C+∡D=360°
∡A=42°
If is an isosceles trapezoid
then
∡A=∡D
so
∡D=42°
and
∡B=∡C
then
2*42°+2*∡C=360°-------> ∡C=[360°-2*42°]/2-----> ∡C=138°
∡C=138°
∡B=138°
therefore
the answer is
the other three angle measures are
42°
138°
138°
