Answer:
The missing measure is 80°
Explanation:
Since the sum of the measures of the angles of the trapezoid=360°
⇒∠DAB+∠ABC+∠BCD+∠CDA=360°
It is given in the question that ∠A=80°, ∠B=100°, ∠C=100° and need to find the measure of ∠D,
⇒80°+100°+100°+∠CDA=360°
⇒280°+∠CDA=360°
⇒d=360°-280°
⇒d=80°
Thus, the missing measure is 80°