Let be a trapezoid with , and . Show that
i. ,
ii. .
Let be a trapezoid with , and . Show that
i. ,
ii. .
i. Let meet at , meet at , and let be the midpoint of . Since , the points and must lie on the segments and respectively.
Since , we have . This implies , and hence .

ii. By Steiner's theorem, , , are collinear. Since , both and lie on the same side as to the perpendicular bisector of . This implies . Now, as , we have . This means .