Feuerbach's theorem
1. How is the incircle defined?
2. How are the excircles defined?
3. Critisize the result on the picture.
4. How do you define the 9-point circle (or the Euler circle or the Feuerbach's circle)?
5. Which triangle is the podar triangle of ACD?
6. What is the content of Feuerbach's theorem?
7. If you keep B and C fixed and move A to the position where D was initially, some points are kept
fixed and some are changed. Complete the following list:
A ® D
D ®
B ® B
C ® C
A´ ® A´
P ® P
Q ®
B´ ®
C´ ®
R ®
A´´ ®
B´´ ®
C´´ ®