How Much Current Flows in the Circular Loop When the Net Magnetic Field Is Zero?

[buckeyes]

Homework Statement

A very long, straight wire carries a current of 0.75 A. This wire is tangent to a single-turn, circular wire loop that also carries a current. The directions of the currents are such that the net magnetic field at the center of the loop is zero. Both wires are insulated and have diameters that can be neglected. How much current is there in the loop?

Homework Equations

http://www.webassign.net/cutnell7e/art/math/cutnell3158c21/math069.gif
http://www.webassign.net/cutnell7e/art/math/cutnell3158c21/math083.gif

The Attempt at a Solution

all i have is a picture drawn of a straight wire with a circular wire loop next to it. i know the formulas but i can't figure out how to put them together

 

[buckeyes]

never mind. i figured it out. it was easier then i was trying to make it. :)