Question 1
Opposite sides of a trapezoid are parallel. So, by the same-side interior angles theorem,

Question 2
Drawing PR, we form congruent triangles PQR and PSR. Thus, using the sum of angles in a triangle,

Question 3
Opposite sides of a trapezoid are parallel. So, by the same-side interior angles theorem,

Question 4
Opposite sides of a trapezoid are parallel. So, by the same-side interior angles theorem,
