Answer:
7.D
8.A
Explanation:
7.
r=√((0-6)²+(0+8)²)=√(36+64)=√100=10
eq. of circle is (x-6)²+(y+8)²=10²
(x-6)²+(y+8)²=100
8.
CM=1/2CD=1/2×60=30
OM=18
OC=√(30²+18²)=√(900+324)=√(1224)=√(4×306)=√(4×9×34)=2×3√34=6√34
radius r=OC=6√34
OF=r=6√34
ON=15
FN=√((6√34)²-15²)=√(1224-225)=√999=√(9×111)=3√111