1. The problem statement, all variables and given/known data A compass needle points 20 degrees E of N outdoors. However, when it is placed 8.0 cm to the east of a vertical wire inside a building, it points 55 degrees E of N. What is the magnitude and direction of the current in the wire? The Earth's field there is 0.50 x 10^ -4 T and is horizontal. 2. Relevant equations I'm thinking I'll need to use B = ( u I ) / (2 r pi) and something involving vectors... 3. The attempt at a solution I really don't even know where to begin with the setup for problem. Do I start with the angles to find a vector sum of something? I just have no idea, sorry. Someone please help walk me through it.