It intersects with the line containing the segment AD at some point E . Consider a triangle ABE . QP is one of its midsegments by the previous reasoning. Finally, One more result that we would like to discuss will be connected with the properties of isosceles trapezoids. If ABCD is an isosceles trapezoid then each pair of its base angles consist of equal angles.
D are equal.
The equality of angles C and B is checked in the same way. Let's construct a line that will pass through C and will be parallel to AB . This line will intersect with AD at some point E . Then ABCE is a parallelogram. But AB is already equal to CD , so the triangle ECD is an isosceles one.