Answer:
∠1 = 50°
∠2 = ∠3 = 130°
Step-by-step explanation:
In an isosceles trapezoid, such as this one, the angles at either end of a base are congruent:
∠1 ≅ 50°
∠2 ≅ ∠3
The theorems applicable to transversals and parallel lines also apply to the sides joining the parallel bases. In particular, "consecutive interior angles are supplementary." That is, angles 1 and 2 are supplementary, for example.
∠2 = 180° -∠1 = 180° -50° = 130°
We already know angle 3 is congruent to this.
∠1 = 50°
∠2 = ∠3 = 130°
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Additional comment
It can be easier to see the congruence of the base angles if you remove the length of the shorter base from both bases. This collapses the figure to an isosceles triangle and makes it obvious that the base angles are congruent.
Alternatively, you can drop an altitude to the longer base from each end of the shorter base. That will create two congruent right triangles at either end of the figure. Those will have congruent corresponding angles.
