Practice problem
Let ABCDABCDABCD be a quadrilateral where m∠DAB=m∠ABC=80∘.m\angle DAB = m\angle ABC = 80^{\circ}.m∠DAB=m∠ABC=80∘. Must ABCDABCDABCD be an isosceles trapezoid? Why or why not?
No because ∠BCD\angle BCD∠BCD and ∠CDA\angle CDA∠CDA are not congruent.
No because ABABAB and CDCDCD may not be parallel.
Yes because ∠BCD\angle BCD∠BCD and ∠CDA\angle CDA∠CDA are congruent.
Yes because ABABAB and CDCDCD are parallel.
Yes because DADADA and BCBCBC are parallel.
Type a concept, like “slope” or “photosynthesis”.
