Math Is Fun Forum

please help me to answer this quetion:
1. in circle with center O, BD is the diameter, Ab and BC are chords, and AB > BC. prove thath angle ABD < angle CBD.
2. let triangle ABC be right triangle with angle A is the right angle. let D, E, and F be the midpoints of AB, AC, and BC, respectively. prove that F is the center of a semicircle which contains A, B, and C

thanks..