
Dayv O. answered 11/19/21
Caring Super Enthusiastic Knowledgeable Geometry Tutor
It is congruent for 1., in parallelogram diagonal makes two congruent triangles. there are logic steps to prove it including assumption implies equal sides. Something like two parallel lines cut by two parallel lines creates equal opposite sides. The diagonal is a shared side. So tringles congruent SSS
#2. same kind of as 1. and then SSS
#3. might not be a parallelogram (a non isosceles trapezoid) and triangle cannot be proven congruent.
#4 makes sure the quadrilateral is rectangle and you can prove triangle congruent.
again A rectangle has equal opposite sides. SSS
#5 does not lead to congruent triangles because the given implies two isosceles triangles but not that they are equal isosceles
Buddy S.
Im sorry, I might have worded the question wrongly, its can the triangles be proven congruent if the statement of the left side is true, so if dc is parallel to ab would they be congruent by which theorem and so on.11/19/21