*R<AB/2 nen AB nam ngoai duong tron
lamda=1.5cm ...
* -AB/lamda\leqk\leqAB/lamda\Leftrightarrow-8/1.5\leqk\leq8/1.5
*-5.33\leqk\leq5.33 \Rightarrowco 11 gia tri ....Tong so diem cuc dai la 2.11=22 diem
nhung do A,B nam ngoai duong trong nen khong tinh 2 diem A,B nen co 20 diem dao dong cuc dai