Answer: Isosceles
Explanation:
Given: AB || DE , BC is a transversal
∠ABC ≅ ∠BCE by Alternate Interior Angles Theorem --> ∠BCE = 80°
∠DCA, ∠ACB, & ∠BCA are supplementary --> ∠ACB = 50°
By the Triangle Sum Theorem, ∠A+∠B+∠C = 180° --> ∠CAB = 50°
Triangle is isosceles because ∠A ≅ ∠C