The radius is 6
Complete the square on the equation and get
(x-6)^2 + (y-6)^2 =36
The circle equation is
(x-h)^2 + (y-k)^2 = r^2
Center(h,k) r=radius
The answer is -8 because -4x2 is -8
Vertical Angles: Theorem and Proof
Theorem: In a pair of intersecting lines the vertically opposite angles are equal. It can be seen that ray \overline{OA} stands on the line \overleftrightarrow{CD} and according to Linear Pair Axiom, if a ray stands on a line, then the adjacent angles form a linear pair of angles.
1. YES 2. NO, correct me if im wrong