Answer:
a. 3.039cm
b.magnetic field is 
Explanation:
Direction of the solenoid magnetic field is along the axis of the solenoid. and magnetic field due to the wire perpendicular to that due to the solenoid.. Magnetic field at r is given by:

Angle of net magnetic field from axial direction is given by:
,
Field due to solenoid:

Field due to wire:

Therefore, r:

Hence, the radial distance is 3.039cm
b.The magnetic field strength is given by:

Hence, the magnetic field is 
Answer:
-2R
Explanation:
The focal length can be calculated using this formula
1/f = (n1/n2-1)(1/r1-1/r2)
1/f = (1/1.33-1)(1/r + 1/r)
= -0.133/1.33(2/R)
F = -2R
The focal length is this