12. Three long, straight wires are mounted on the vertices of an equilateral triangle as shown in the figure. The wires carry currents of I1 = 8.50 A, 1, = 5.50 A, and Is = 4.50 A. Each side of the triangle has a length of 28.0 cm, and the point (A) is located half way between (1, ) and (12) along one of the sides. Find the magnitude of the magnetic field at point (A). T C. O A