At a point in a material subjected to two direct stresses on planes at right angles, the resultant stress on a plane \(A\) is \(80 \mathrm{MPa}\) inclined at \(30^{\circ}\) to the normal, and on plane \(B\) is \(40 \mathrm{MPa}\) inclined at \(45^{\circ}\) to the normal. Find the principal stresses and show the position of the two planes \(A\) and \(B\) relative to the principal stresses.