Math Is Fun Forum

sunnalov

Member

Registered: 2008-12-14

Posts: 1

proof of circle

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..

macy

Guest

Re: proof of circle

1. angle CBD stands on arc CD, angle ABD stands on arc AD. Because arc AD < arc CD therefore angle ABD < angle CBD

2. As ABC is the right angle triangle with BC is the diameter of the circle therefore A,B,C must be on the semicicle

You need to look at the cicle geometry theorem for these questions