40 mm 12 mm 40 mm 30 mm 10 mm PROBLEM 6.40 Knowing that a given vertical shear V causes a maximum shearing stress of 50 MPa in a thin-walled member having the cross section shown, determine the corresponding shearing stress (a) at point a, (b) at point b, (c) at point c. 50 mm 10 mm 30 mm (a vertical, b horizontal, c vertical)