1. Sphere C(-2,1,-3), radius=7. T plane at (4,-2,-1)=? (a) 6x-3y+2z=0 (b) r.(6,3,2)=28 (c) 5x-3y-2z=28 (d) r.(6/7,-3/7,2/7)

2. Sphere (x-1)²+(y-5)²+(z-2)²=49 and planr r.(-2,-6,-3)=0 form which circle?(a) (x-1)²+(y-5)²+(z-2)²=19.53 (b) C(0,0,0), radius=4.42 (c) radius=4.42, C(-5/7,-1/7,-4/7) (d) r²=19.53, C(-1,-1,-1)

Please help me, I really don't understand this sphere stuff!