The radius of the circle with the polar equation r2-8r(√3cosθ+sinθ)+ 15 = 0 is
A. 8
B. 7
C. 6
D. 5
The polar equation of the line perpendicular to the line sin θ- cos θ =1/r and passing through the point (2,π/6) is
A. sin θ + cos θ =(√3 +1 )/r
B. sin θ - cos θ =(√3 +1 )/r
C. sin θ + cos θ =(√3 -1 )/r
D. cos θ - sin θ =√3 /r