1. Check the picture below. ABC is an isosceles triangle with vertex C, so m(A)=m(B) = a degrees.
2. For ABED to be a trapezoid, DE must be parallel to AB.
3. DE is parallel to AB so the following is true:
m(CAB)=m(CDE)=a degrees as CAB and CDE are alternate interior angles. (angles F)
m(CBA)=m(CED)=a degrees, as CBA and CED are alternate interior angles.
4.
a+a+32=180
2a=148
a= 148/2= 74 (degrees)
5.Answer : C
the measure of an acute base angle of the trapezoid=a=74 degrees
